On Thu, 20 Jul 2017 04:29:26 -0000 (UTC), Mad Roger
wrote:

On Wed, 19 Jul 2017 22:59:45 -0400,
wrote:

So 20mpg is really from 19mpg to 21mpg, which makes calculation difficult
(when I was looking up the wheel size stuff earlier today, Consumer Reports
said as much so that's why I'm curious how close you think you can get to a
repeatably precise figure (yes, both repeatable, and precise).
With the fuel mileage rig I had (for carbureted vehicles) you could
see the differnce made by changing tire pressure by a few PSI if the
wind didn.t change. You could see the difference from winding down a
window.

Take everything I say with a grain of salt because I'd have to dig up the
references of where I got this idea that even the EPA can't get better than
4% (as I recall), and they don't measure volume (since that's inaccurate).
They measure weight. And they used, as I recall, plastic bags filled with a
known *weight* of fuel.

In addition, they ran on test course, and they repeated the tests.
And even then, they couldn't get better than 4% as I recall.

Unless I dig up the reference, that's all hearsay, but, as I recall, nobody
is going to get accuracies and repeatabilities anywhere near decimal places
at home if they're not repeating the tests under extremely well controlled
circumstances and weighing the fuel consumed.
Weighing the fuel is NOT required if the tests are done at the same
temperature - which would be a requirement for accuracy in fuel
mileage measurementin any case due to the difference in air density.

On 7/20/2017 7:59 AM, Mad Roger wrote:


Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
http://www.consumerreports.org/fuel-...or-ac-running/
By Consumer Reports, June 18, 2017

Q. Does a car use more gasoline when you drive with the windows rolled down
or the air conditioning turned on?

A. ´We found that on an 85-degree day, running the A/C can reduce fuel
economy by 1 to 4 mpg, depending on the car....[while] the effect of
opening the windows at 65 mph did not measurably reduce fuel economy,¡


I'm not doubting their test results but that sounds like a broad blanket
statement. What particular car and engine? Will you get that result
with a Tesla, F-150 and 1987 Chrysler Cordova?

Both AC compressors and auto aerodynamics have improved over the years.
In any case, if it is 85 degrees, I'll have the AC on. My present car
has the best AC of any I've ever had since my first car with ac, a '68
Olds Vista Cruiser I bought in 1971.

On Thu, 20 Jul 2017 11:59:40 -0000 (UTC), Mad Roger
wrote:

On Wed, 19 Jul 2017 23:07:03 -0600,
rbowman wrote:

With my scanguage calibrated to my GPS, over a 2 or 3 tank run I can
be accurate to tenths

Mad Roger lives in the past. What I find cute with the scangauge set for
instantaneous reading is when you get off the throttle, the injectors
shut off, and the reading goes to 99.999 mpg.

Remember I said 4% accuracy, so let's see if my statement holds water over
the next few days. If that is correct, then anyone quoting accuracy with a
decimal place in it is ridiculously misled.

Doing a quick search, Car & Driver says the EPA gets to 1% with what
appears to be a 350 million dollars investment in tools.

"Measuring fuel economy during the tests is likewise hugely complex, which
is why the automakers and the EPA both follow precisely the same protocol.
For openers, the chemical composition of fuel varies slightly, so simply
retrieving it from a local gas station won¡¦t produce repeatable results.
The EPA has a specialized company manufacture small batches of consistent
fuel, which is 93 octane ... Before being used, the gas is analyzed to
measure its properties, and fuel economy is then calculated based on the
measured carbon content of the various tailpipe emissions¡Xunburned
hydrocarbons, carbon dioxide (CO2), carbon monoxide (CO), methane (CH4),
and oxides of nitrogen (NOx)¡Xthat are collected in bags made of a special
Kynar plastic. A $350,000 gas-analyzing machine then makes minute
measurements. The one-percent accuracy of this machine from Japanese
company Horiba is amazing considering the minuscule amounts of some of the
exhaust constituents¡Xsome in quantities as low as a half-dozen parts per
million.
http://www.caranddriver.com/features...economy-page-2

So what's 1% to a typical consumer?

Reading the whole article, I can't tell if that 1% is 1% of 20mpg or 1% of
18 gallons.

If it's 1% of, say, 20 mpg, then that could mean it's +/- 0.2 mpg (or 19.8
mpg to 20.2 mpg).
If it's 1% of, say, 20 gallons, then that could mean it's +/- 0.2 gallons
(or 19.8 gallons to 20.2 gallons).
The problem is getting an accurate reesult over varying conditions.
Getting extremely accurate results in a fixed condition is simple.
Same road, same speed, same weather conditions, repeatability is
excellent and simple equipment can be very accurate. For instance,
calibrated fuel supply, running start on measured distance at
predeteermined speeds - make modification and retest.

On 7/20/2017 1:01 AM, rbowman wrote:
On 07/19/2017 04:10 PM, wrote:
Cheap old motorhead farts notwithstanding ..
When I can't avoid visiting the city - I enjoy watching
the Kids with their lowered cars trying to go
into/out of a driveway ... duh. Really ?
At what point does reality kick in ?
John T.

Nothing changes. Remember the chopped and channeled bathtub Mercs that
high centered on a cigarette butt?

Then there are the hoppers:

https://www.youtube.com/watch?v=UC491a3UFoo

I remember the Mercs. Wish I had the skills to build one. The 50's and
60's were the golden age of custom cars.

On 07/20/2017 07:09 AM, Ed Pawlowski wrote:
On 7/20/2017 1:01 AM, rbowman wrote:
On 07/19/2017 04:10 PM, wrote:
Cheap old motorhead farts notwithstanding ..
When I can't avoid visiting the city - I enjoy watching
the Kids with their lowered cars trying to go
into/out of a driveway ... duh. Really ?
At what point does reality kick in ?
John T.

Nothing changes. Remember the chopped and channeled bathtub Mercs that
high centered on a cigarette butt?

Then there are the hoppers:

https://www.youtube.com/watch?v=UC491a3UFoo

I remember the Mercs. Wish I had the skills to build one. The 50's and
60's were the golden age of custom cars.

I worked in Ft. Wayne for a while. Indiana is big on car stuff since
there isn't a whole lot of outdoor recreation opportunities. Fairmount
was James Dean's boyhood home and is where he is buried so they have a
James Dean Festival every year. The Mercs roll in from all over.

It wasn't a custom, but my soft spot is the '51 Ford from 'Thunder
Road'. There is a nice one around town with the appropriate vanity plate.

On 07/20/2017 05:59 AM, Mad Roger wrote:
Here's a seemingly expensive "fuel economy meter" which shows the
complexity of calibration, heated probes, high-speed sampling, auto zero,
etc. whose specs show a "resolution" of "± 2% reading" and a "repatability"
of "±2 % of reading" with a "span drift" of "±2 % of reading"
http://mustangae.com/products-servic...+Economy+Meter
http://mustangdyne.com/mustangae/upd...09/MAE-FEM.pdf

OBCII. You are plugged into the car's computer system, air mass sensors,
injector timing, the whole works.

On Thursday, July 20, 2017 at 12:29:28 AM UTC-4, Mad Roger wrote:
On Wed, 19 Jul 2017 22:34:44 -0400,
wrote:

The reality is that it seems the variables I tried to keep out of the
original question (for example tire width, tread pattern, rubber material,
inflation pressure, unsprung weight, etc.) can make more of a difference
than does the larger diameter tire.
Don't bother arguing with Trader - he's CLUELESS

I can tell who knows what they're talking about and who doesn't so thanks
for the warning.


Nice. I explained the physics to you several times here and why
your logic of equating more torque at the wheel with better fuel economy
was wrong. I even gave you simple examples of the physics, using
torque to lift a rock or to ride a bicycle up hill. While torque
can be changed to more easily lift a rock or to get a bike up a
hill, the ENERGY used is exactly the same. It's physics 101.

What did I see back from you? NOTHING. No acknowledgment of the issue,
no sign that you learned a damn thing. In fact, you tried to obfuscate
the issue, suggest that I'm wrong, by then dragging differing speeds
which then affect air resistance. Totally bogus and dishonest because
it's not the issue at hand and your car example with tires was a constant
speed, where wind resistance is the SAME and only the tire diameter
changes.

Bob F explained along similar lines with the gearing ratios in cars.
We were both on the same page, from our very first posts, telling you
the same thing, that you
had it wrong. And along the way, you even kept saying that "while
we would intuitively think...." when it was only YOU who was making
that incorrect argument. So, now along comes Clare, who's also telling
you the same damn thing, and now you thank him for slamming me
and have the nerve to imply that I don't know what I'm talking about?

Why don't you and Clare got get a room and jerk each other off, idiot.





Pretty much if someone says something (even me) without backing it up with
a reference, it's just hearsay.


You're so full of ****. I showed you clear, simple physics examples of why
you had it wrong, and you just ignored it, instead citing an article
from the LA Times written by some reporter who probably has a degree
in journalism and who's first thought when the word Newton is mentioned
is a type of cookie. And even that article told you the same damn thing,
then you make it look like you're the genius who finally figured out
your "mystery".

ROFL

On 07/20/2017 05:59 AM, Mad Roger wrote:
Doing a quick search, Car & Driver says the EPA gets to 1% with what
appears to be a 350 million dollars investment in tools.

The EPA has a much more complex problem. They are not measuring the fuel
economy of a particular vehicle in the short term. They are attempting
to compare apples and oranges

On Thu, 20 Jul 2017 08:47:39 -0400,
wrote:

None of the articles seemed surprised at the losses, although the consumer
reports article discussed that the measurements were such that they were
within their measurement margin of error.
Because consumer reports does not do a terribly scientific
comparison.

We could wax prolifically on Consumer Reports, where it would delve into
the fact that they're a "business" (sort of) and that their customers want
to hear contrary stuff (remember the Bose speakers "wandering" around the
room lawsuits that proved what I'm asserting?).

However ...

This is Usenet for heaven's sake.

So, if you forced me at gunpoint to choose to believe something that a
Consumer Reports engineer published as fact, versus something someone on
Usenet posted as fact ... whom do you think I'd choose to save my life?

On Thu, 20 Jul 2017 07:55:21 -0700 (PDT),
trader_4 wrote:

Nice. I explained the physics to you several times here and why
your logic of equating more torque at the wheel with better fuel economy
was wrong.

You must have noticed that I did not dispute you on any of that???????

I even gave you simple examples of the physics, using
torque to lift a rock or to ride a bicycle up hill. While torque
can be changed to more easily lift a rock or to get a bike up a
hill, the ENERGY used is exactly the same. It's physics 101.

While I took physics, chemistry, organic chemistry and biochemistry in
college (in addition to immunology, phsyiology, microbiology, etc.), I
wasn't all that great at calculus and phsysics.

So you'll note that I didn't dispute anything you said, as I'm not looking
here to either argue outside my realm of knowledge, nor to try to prove
that I'm right (since I only care to find the answer to the question).

I think we all found the answer to the question.
Do you disagree with the answer we all found?

What did I see back from you? NOTHING. No acknowledgment of the issue,
no sign that you learned a damn thing. In fact, you tried to obfuscate
the issue, suggest that I'm wrong, by then dragging differing speeds
which then affect air resistance. Totally bogus and dishonest because
it's not the issue at hand and your car example with tires was a constant
speed, where wind resistance is the SAME and only the tire diameter
changes.

It was a poor choice of mine to include a *forum* article, which you will
note that I didn't include again in this discussion.

After that one physics forum article, I realized that I had better stick to
the more reliable ones such as the Cooper Tire and Consumer Reports and Car
and Driver.

So, my mistake was including the physics forum, where anyone can say
anything without having to be held accountable to what they said.

Bob F explained along similar lines with the gearing ratios in cars.
We were both on the same page, from our very first posts, telling you
the same thing, that you had it wrong.

What matters here is the answer to the question:
Q: What's the performance difference between 15 inch, 16 inch and 17 inch
tires (all else equal)?

The answer was summarized, to which you are now responding, but, you're not
responding to the answer of the question but to a tangental reference.

As I told others, you can shoot down one reference, but since they all say
essentially the same thing, you have to shoot down all the references if
you're going to take that approach to win a pet argument you seem to want
to win.

I am not here to argue the physics and I apologize for bringing in that
physics forum because I am not qualified to debate the physics (which you
will notice I didn't do).

I just bring in *more* and *more* (hopefully reliable) articles that say
the same thing, which is that you'd be hard pressed to get *any*
performance benefit out of larger diameter fitments - but it's possible -
if you are either luck - or if you tightly control the variables.

In fact, I can't find a *single* reliable article that claims otherwise,
where you may note I don't have skin in the game since I'm not the one
purchasing larger diameter fitments.

And along the way, you even kept saying that "while
we would intuitively think...." when it was only YOU who was making
that incorrect argument.

The problem with making such a patently false statement is that every false
statement you make counts against your reliability (which is the way
factual discussions work - whether you or I like it or not).

We can go back to the original but it certainly was someone else who said
that the fuel economy on the highway would be better merely because of the
increase in distance traveled per wheel rotation.

If you find me making claims that are untrue, you're welcome (and
encouraged) to call me out to prove them, so if you want me to go back and
prove that statement above, I will.

So, now along comes Clare, who's also telling
you the same damn thing, and now you thank him for slamming me
and have the nerve to imply that I don't know what I'm talking about?

I apologize that you thought that I was saying something about "you" in
that response.

I understand that you misinterpreted my response to Clare because *anyone*
might conclude what you just concluded - so even I might have concluded the
same thing you just concluded based on the he-said-she-said trail of
message ids.

The problem is that Usenet is, at best, a mere two-dimensional facsimile of
a multi-person multi-dimensional conversation, where my statement to Clare
was actually *meant* to be a generality.

Specifically, truth be openly told, when I responded to Clare, I wasn't
thinking of any particular person. I was thinking "in general", where I can
tell who knows what they're talking about.

Anyone can tell actually ...

So I wasn't talking about you specifically.

What I'm talking about is, for example, that *someone* (I don't remember
who) said that, for example, you get increased gas mileage at speed, where,
when I tested that assumption in the literature, I found that you'd be
really hard pressed to get increased anything at speed with just a change
in tire fitment to larger diameters.

So, that person either was giving a generality (which happens), or they
didn't know the complexities (which happens).

The statement should have been more like what my summary was, which is that
you "can" get better mileage out of larger-diameter fitments, but you're
most likely not going to get better mileage unless you're either lucky, or
you really know what you're doing and then you control for the complex set
of variables involved (which include weight, resistance, handling, patch
width, torque curves, etc.).

Why don't you and Clare got get a room and jerk each other off, idiot.

You'll note that when I'm wrong, I admit it, and that when someone else is
wrong, I tell them that I think they're wrong - but - I don't resort to
calling them an idiot until and unless they actually show themselves to be
an idiot.

I'll conveniently forget you just called me an idiot because I don't really
care, here, to defend my intelligence to someone who just made a bunch of
claims that I already defended myself on.

As you can tell, I hope, like any good scientist, I don't care if my
intuition is correct or not, and if it's not correct, I'll just form a new
intuition that is correct, where the end result of this thread seems to be
that the larger fitment, in and of itself, would only result in greater mpg
performance if the stars are lined up (mostly on the torque curve, and
secondarily on the contact patch width but vehicle height and resulting
drag coefficient also play a role if they're affected).

Do you agree with that balanced assessment?

You're so full of ****.

When someone repeatedly attacks someone who isn't attacking back, and who
didn't (mean to) start the attack process, I'm going to have to let others
defend my actions to you, (or not).

I showed you clear, simple physics examples of why
you had it wrong, and you just ignored it, instead citing an article
from the LA Times written by some reporter who probably has a degree
in journalism and who's first thought when the word Newton is mentioned
is a type of cookie.

I don't remember who it was that deprecated the LA Times article, but I
remember my response, which is a typical response of a scientist, which is
that it's fine that they deprecate that one article, but then how do they
manage to deprecate all the others that said essentially the same thing?

Car & Driver.
Consumer Reports .
Dunn Tire.

If someone deprecates an article, but then they can't deprecate that a half
dozen more reliable articles say the same thing, then what good is that
single deprecation?

I don't know their psychological makeup, which is another huge problem on
Usenet, but my point here is that the science is what should win.

Not our emotions to the contrary of science.

And even that article told you the same damn thing,
then you make it look like you're the genius who finally figured out
your "mystery".

While it's normal for people like you on Usenet to get emotional, you seem
to think this is a game of who is smarter than whom.

It's not.

ROFL

What matters is the science so if you find the science funny, that's fine.

I think, together, we have come to a scientifically valid conclusion in
this thread, which is that the average mom-and-pop would be hard pressed to
gain any performance benefit out of a larger-diameter fitment - but if they
controlled the key variables (such as the torque curve, tire contact patch
width, vehicle height and aerodynamics, and suspension alignment) they
certainly "could" get better miles per gallon out of the larger fitment.

Does everyone agree with that statement?
I'm sure there are plenty who disagree.

It will be left for the others to agree or disagree with my assessment,
which is my obligation to make given that I initiated the question but the
right answer is never a given so my statement remains to stand the test of
objections from others.

Such is science.

On Thu, 20 Jul 2017 08:39:22 -0600,
rbowman wrote:

Here's a seemingly expensive "fuel economy meter" which shows the
complexity of calibration, heated probes, high-speed sampling, auto zero,
etc. whose specs show a "resolution" of "± 2% reading" and a "repatability"
of "±2 % of reading" with a "span drift" of "±2 % of reading"
http://mustangae.com/products-servic...+Economy+Meter
http://mustangdyne.com/mustangae/upd...09/MAE-FEM.pdf

OBCII. You are plugged into the car's computer system, air mass sensors,
injector timing, the whole works.

Since mpg measurement at home is a tangent offshoot from mpg performance of
larger-diameter wheels and tires, I opened a separate thread with the
science guys over here

https://groups.google.com/forum/#!to...ir/PT3YdPClM7g
What is the realistic accuracy & precision of typical consumer MPG
calculations (tripmeter miles/pump gallons)

On Thu, 20 Jul 2017 08:56:59 -0600,
rbowman wrote:

The EPA has a much more complex problem. They are not measuring the fuel
economy of a particular vehicle in the short term. They are attempting
to compare apples and oranges

That could be the case that the EPA cares about something else (and they
can be driven by politics) - but - they must be subject to the scrutiny of
scientists at the car companies - so - we can assume they're held to a
higher standard than the mom and pop is who claims mpg figures with decimal
places.

Since MPG measurement accuracy & repeatability is a slightly different
subject from tire performance, we can take this subject over to this
thread:

What is the realistic accuracy & precision of typical consumer MPG
calculations (tripmeter miles/pump gallons)
https://groups.google.com/forum/#!to...ir/PT3YdPClM7g

On Thu, 20 Jul 2017 09:00:41 -0400,
wrote:

The problem is getting an accurate reesult over varying conditions.
Getting extremely accurate results in a fixed condition is simple.
Same road, same speed, same weather conditions, repeatability is
excellent and simple equipment can be very accurate. For instance,
calibrated fuel supply, running start on measured distance at
predeteermined speeds - make modification and retest.

I agree. But I suspect most people don't understand what you just wrote.

My rule-of-thumb take-it-with-a-grain-of-salt "assumption" is that anyone
quoting decimal places using "home methods" is probably not understanding
what you just said.

There's now a separate thread, with science guys on it, over he

What is the realistic accuracy & precision of typical consumer MPG
calculations (tripmeter miles/pump gallons)
https://groups.google.com/forum/#!to...ir/PT3YdPClM7g

On Thu, 20 Jul 2017 08:50:37 -0400,
wrote:

Weighing the fuel is NOT required if the tests are done at the same
temperature - which would be a requirement for accuracy in fuel
mileage measurementin any case due to the difference in air density.

Being the progeny of two PhD chemists, I'm well aware of density, but are
you sure every mom and pop who "claims" their spectacularly "accurate" 22.9
mile-per-gallon numbers understands what you and I both know?

Do they realize that you have to keep the *entire* test at the same
atmospheric conditions, and where the typical mom and pop doesn't do that
for an entire tank of gas (which might take a week to use up during which
time the atmospheric conditions change greatly).

Do they even know what "test conditions" they're testing and do they run
"controls"?

Point is, my assertion (as yet unproven) is that the mpg figures with a
decimal point in them that people "say", are an indication of their
ignorance of what they measured.

As for what accuracy "can" people measure with the typical tripmeter
divided by pumpmeter test, I opened a separate thread on that topic because
it's a valid question (where I added the science & car guys).

https://groups.google.com/forum/#!to...ir/PT3YdPClM7g
What is the realistic accuracy & precision of typical consumer MPG
calculations (tripmeter miles/pump gallons)

On Thu, 20 Jul 2017 08:46:17 -0400,
wrote:

Back when I had the use of the unit, AC was not as efficient as it is
today, but at low speeds it was more efficient to open the windows,
although a lot less effective here where relative humidity is quite
high. At highway speeds the extra drag from open windows and all the
bufetting inside the car made the AC more efficient. I strongly
suspect the same is still true today with more efficient AC - perhaps
the "transition speed" is lower today.

I know running with the windows open at 60 MPH across Kansas and
Oklahoma back in 1976 did NOTHING to make the cab of my 1957 Fargo
more comfortable, so whatever the mileage hit for AC, IT WAS ON!!!!

I found *plenty* of articles which debunk the A/C myth.

I think the A/C myth is born out of the same things most myths are born out
of, e.g., the high-octane myth, which is that marketing departments are
very good at planting the seeds of urban myths, because they understand, I
suspect, that most people trust their intuition more so than they trust
facts to the contrary.

Also most people, I suspect, hold on to long-held beliefs, and can't shake
them, no matter what.

Luckily, for you, the reason you can get good information out of me, is
that I hold neither of those two traits all too strongly. While everyone
holds those two traits, I can easily change my mind if you show me facts to
the contrary, and, I don't trust my own intuition as much as I trust
reliable facts to the contrary.

Having been raised by two PhD chemists, I mainly trust that which I can
reliably reference.

But, particularly, I trust an article that *knows* the myth, and debunks
it, rather than an article that doesn't indicate any knowledge of the myth,
and just propagates it.

I don't own a pickup so I just skimmed this part, but, as an example, CR,
released today an article that shows that leaving the tailgate open on a
pickup truck, apparently, worsens gas mileage.
http://www.consumerreports.org/cro/c...nomy/index.htm

On Thu, 20 Jul 2017 08:58:28 -0400,
Ed Pawlowski wrote:

Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
http://www.consumerreports.org/fuel-...or-ac-running/
By Consumer Reports, June 18, 2017

Q. Does a car use more gasoline when you drive with the windows rolled down
or the air conditioning turned on?

A. ´We found that on an 85-degree day, running the A/C can reduce fuel
economy by 1 to 4 mpg, depending on the car....[while] the effect of
opening the windows at 65 mph did not measurably reduce fuel economy,¡


I'm not doubting their test results but that sounds like a broad blanket
statement. What particular car and engine? Will you get that result
with a Tesla, F-150 and 1987 Chrysler Cordova?

Both AC compressors and auto aerodynamics have improved over the years.
In any case, if it is 85 degrees, I'll have the AC on. My present car
has the best AC of any I've ever had since my first car with ac, a '68
Olds Vista Cruiser I bought in 1971.

That article was published *today* in the print magazine (it says), so, we
can presume they used a recent model year vehicle - but maybe more is in
the print article. (Anyone have it handy?)

The first line of the online version I quoted says they tested lots of cars
though...
"Weve tested this at various temperatures with multiple vehicles,€� says
Jake Fisher, CRs director of auto testing "

BTW, there were quite a few articles on the net which said the same thing.

So if you want to beat up the CR article, I can show you plenty more which
say the same thing that you'll also have to beat up.

BTW, most people trust their own intuition more than they trust facts to
the contrary, so you might be surprised when you read the part about what
they found out when they tested cars that SAID to use high octane fuel, but
CR tested them with the low-octane (regular) fuel instead.
http://www.consumerreports.org/cro/c...nomy/index.htm

On Thursday, July 20, 2017 at 2:14:02 PM UTC-4, Mad Roger wrote:
On Thu, 20 Jul 2017 07:55:21 -0700 (PDT),
trader_4 wrote:

Nice. I explained the physics to you several times here and why
your logic of equating more torque at the wheel with better fuel economy
was wrong.

You must have noticed that I did not dispute you on any of that???????

Instead of acknowledging it, you totally moved the goal posts by
dragging changing speed into it. And then you went on with more
posts, as if you never got it. I'm not sure that even now you
understand that torque and energy/work are different things.

And you freely joined in with Clare, when he slammed me, you thanked
him. You didn't say, "but Trader explained the physics, what about
those examples, etc?"



I even gave you simple examples of the physics, using
torque to lift a rock or to ride a bicycle up hill. While torque
can be changed to more easily lift a rock or to get a bike up a
hill, the ENERGY used is exactly the same. It's physics 101.

While I took physics, chemistry, organic chemistry and biochemistry in
college (in addition to immunology, phsyiology, microbiology, etc.), I
wasn't all that great at calculus and phsysics.

So you'll note that I didn't dispute anything you said, as I'm not looking
here to either argue outside my realm of knowledge, nor to try to prove
that I'm right (since I only care to find the answer to the question).


You sure changed the goal posts when I gave you the example of riding
a bicycle up hill. You then brought up wind resistance and the speed
potentially being different. Which of course it doesn't have to be,
it's just obfuscation when I was making a clear point on the physics.
You weren't talking about a car with different diameter tires, one
going 50, the other 65mph were you?



I think we all found the answer to the question.
Do you disagree with the answer we all found?


Why would I disagree with what I and Bob F were telling
you from the start?



What did I see back from you? NOTHING. No acknowledgment of the issue,
no sign that you learned a damn thing. In fact, you tried to obfuscate
the issue, suggest that I'm wrong, by then dragging differing speeds
which then affect air resistance. Totally bogus and dishonest because
it's not the issue at hand and your car example with tires was a constant
speed, where wind resistance is the SAME and only the tire diameter
changes.

It was a poor choice of mine to include a *forum* article, which you will
note that I didn't include again in this discussion.

After that one physics forum article, I realized that I had better stick to
the more reliable ones such as the Cooper Tire and Consumer Reports and Car
and Driver.

So, my mistake was including the physics forum, where anyone can say
anything without having to be held accountable to what they said.


I'd say your mistake was refusing to address the physics examples
I gave you and instead continuing on in the wilderness. And then
jumping on me with Clare, who by the way, told you the same things
that Bob F and I had.




Bob F explained along similar lines with the gearing ratios in cars.
We were both on the same page, from our very first posts, telling you
the same thing, that you had it wrong.

What matters here is the answer to the question:
Q: What's the performance difference between 15 inch, 16 inch and 17 inch
tires (all else equal)?

The answer was summarized, to which you are now responding, but, you're not
responding to the answer of the question but to a tangental reference.

I'm responding to the fact that it's annoying to tell you that
you were wrong, show you clear physics examples, and then you
just continue to go off in the wilderness and then join in with
Clare insulting me, when Clare is telling you the same damn thing.




As I told others, you can shoot down one reference, but since they all say
essentially the same thing, you have to shoot down all the references if
you're going to take that approach to win a pet argument you seem to want
to win.


Good grief, he we go again. The only one needing to be shot down here
was you.




I am not here to argue the physics

And yet physics is what it's all about. You had the misconception that
torque equals energy/work, it doesn't. That was your fundamental misconception from the beginning.


and I apologize for bringing in that
physics forum because I am not qualified to debate the physics (which you
will notice I didn't do).


But you are debating physics by talking about torque and energy.



I just bring in *more* and *more* (hopefully reliable) articles that say
the same thing, which is that you'd be hard pressed to get *any*
performance benefit out of larger diameter fitments - but it's possible -
if you are either luck - or if you tightly control the variables.


Which is what we were trying to tell you from the beginning.


In fact, I can't find a *single* reliable article that claims otherwise,
where you may note I don't have skin in the game since I'm not the one
purchasing larger diameter fitments.

And along the way, you even kept saying that "while
we would intuitively think...." when it was only YOU who was making
that incorrect argument.

The problem with making such a patently false statement is that every false
statement you make counts against your reliability (which is the way
factual discussions work - whether you or I like it or not).

It's not patently false and I'll stake my reliability in this
thread against yours any day.



We can go back to the original but it certainly was someone else who said
that the fuel economy on the highway would be better merely because of the
increase in distance traveled per wheel rotation.

Maybe someone else did say it once, but both Bob F and I were telling you over
and over, that it isn't so. I gave you those simple physics examples.
Yet you kept saying "we intuitively think", when it was only you
that kept arguing that, post after post.





If you find me making claims that are untrue, you're welcome (and
encouraged) to call me out to prove them, so if you want me to go back and
prove that statement above, I will.

So, now along comes Clare, who's also telling
you the same damn thing, and now you thank him for slamming me
and have the nerve to imply that I don't know what I'm talking about?

I apologize that you thought that I was saying something about "you" in
that response.


Well, like I said, you could have said but what about the physics
examples Trader provided? Examples that you refused to acknowledge,
address or learn from. Instead you just thanked him when he
slammed me.



I understand that you misinterpreted my response to Clare because *anyone*
might conclude what you just concluded - so even I might have concluded the
same thing you just concluded based on the he-said-she-said trail of
message ids.

The problem is that Usenet is, at best, a mere two-dimensional facsimile of
a multi-person multi-dimensional conversation, where my statement to Clare
was actually *meant* to be a generality.

Specifically, truth be openly told, when I responded to Clare, I wasn't
thinking of any particular person. I was thinking "in general", where I can
tell who knows what they're talking about.

Anyone can tell actually ...

So I wasn't talking about you specifically.

What I'm talking about is, for example, that *someone* (I don't remember
who) said that, for example, you get increased gas mileage at speed, where,
when I tested that assumption in the literature, I found that you'd be
really hard pressed to get increased anything at speed with just a change
in tire fitment to larger diameters.

So, that person either was giving a generality (which happens), or they
didn't know the complexities (which happens).

The statement should have been more like what my summary was, which is that
you "can" get better mileage out of larger-diameter fitments, but you're
most likely not going to get better mileage unless you're either lucky, or
you really know what you're doing and then you control for the complex set
of variables involved (which include weight, resistance, handling, patch
width, torque curves, etc.).

Why don't you and Clare got get a room and jerk each other off, idiot.

You'll note that when I'm wrong, I admit it, and that when someone else is
wrong, I tell them that I think they're wrong - but - I don't resort to
calling them an idiot until and unless they actually show themselves to be
an idiot.

I'll conveniently forget you just called me an idiot because I don't really
care, here, to defend my intelligence to someone who just made a bunch of
claims that I already defended myself on.

As you can tell, I hope, like any good scientist,

ROFL, now that's special. What scientist doesn't understand physics
101? Or even better, won't *engage* on the clear, simple physics
examples that went straight to the core of the issue?



I don't care if my
intuition is correct or not, and if it's not correct, I'll just form a new
intuition that is correct, where the end result of this thread seems to be
that the larger fitment, in and of itself, would only result in greater mpg
performance if the stars are lined up (mostly on the torque curve, and
secondarily on the contact patch width but vehicle height and resulting
drag coefficient also play a role if they're affected).

Do you agree with that balanced assessment?

You're so full of ****.

When someone repeatedly attacks someone who isn't attacking back,

Repeatedly is it? I made one post, where I was fed up. Prior
to that, I made many posts and saw you ignore or worse, obfuscate them.
Changing speed and wind resistance? Really?


and who
didn't (mean to) start the attack process, I'm going to have to let others
defend my actions to you, (or not).

I showed you clear, simple physics examples of why
you had it wrong, and you just ignored it, instead citing an article
from the LA Times written by some reporter who probably has a degree
in journalism and who's first thought when the word Newton is mentioned
is a type of cookie.

I don't remember who it was that deprecated the LA Times article, but I
remember my response, which is a typical response of a scientist,

ROFL. A scientist uses an LA Time story instead of discussing
the simple physics examples?



which is
that it's fine that they deprecate that one article, but then how do they
manage to deprecate all the others that said essentially the same thing?

Car & Driver.
Consumer Reports .
Dunn Tire.

All of which are consistent with what I and Bob F told you.



If someone deprecates an article, but then they can't deprecate that a half
dozen more reliable articles say the same thing, then what good is that
single deprecation?

I don't know their psychological makeup, which is another huge problem on
Usenet, but my point here is that the science is what should win.

Not our emotions to the contrary of science.

And even that article told you the same damn thing,
then you make it look like you're the genius who finally figured out
your "mystery".

While it's normal for people like you on Usenet to get emotional, you seem
to think this is a game of who is smarter than whom.

It's not.


Good thing then, because you'd lose.



ROFL

What matters is the science so if you find the science funny, that's fine.


This from the guy who ignored the simple physics examples that go
right to the core.



I think, together, we have come to a scientifically valid conclusion in
this thread, which is that the average mom-and-pop would be hard pressed to
gain any performance benefit out of a larger-diameter fitment - but if they
controlled the key variables (such as the torque curve, tire contact patch
width, vehicle height and aerodynamics, and suspension alignment) they
certainly "could" get better miles per gallon out of the larger fitment.

Does everyone agree with that statement?
I'm sure there are plenty who disagree.

It will be left for the others to agree or disagree with my assessment,
which is my obligation to make given that I initiated the question but the
right answer is never a given so my statement remains to stand the test of
objections from others.

Such is science.

Yeah, science. ROFL!

On Thu, 20 Jul 2017 18:14:04 -0000 (UTC), Mad Roger
wrote:

On Thu, 20 Jul 2017 08:46:17 -0400,
wrote:

Back when I had the use of the unit, AC was not as efficient as it is
today, but at low speeds it was more efficient to open the windows,
although a lot less effective here where relative humidity is quite
high. At highway speeds the extra drag from open windows and all the
bufetting inside the car made the AC more efficient. I strongly
suspect the same is still true today with more efficient AC - perhaps
the "transition speed" is lower today.

I know running with the windows open at 60 MPH across Kansas and
Oklahoma back in 1976 did NOTHING to make the cab of my 1957 Fargo
more comfortable, so whatever the mileage hit for AC, IT WAS ON!!!!

I found *plenty* of articles which debunk the A/C myth.

I think the A/C myth is born out of the same things most myths are born out
of, e.g., the high-octane myth, which is that marketing departments are
very good at planting the seeds of urban myths, because they understand, I
suspect, that most people trust their intuition more so than they trust
facts to the contrary.

Also most people, I suspect, hold on to long-held beliefs, and can't shake
them, no matter what.

Luckily, for you, the reason you can get good information out of me, is
that I hold neither of those two traits all too strongly. While everyone
holds those two traits, I can easily change my mind if you show me facts to
the contrary, and, I don't trust my own intuition as much as I trust
reliable facts to the contrary.

Having been raised by two PhD chemists, I mainly trust that which I can
reliably reference.

But, particularly, I trust an article that *knows* the myth, and debunks
it, rather than an article that doesn't indicate any knowledge of the myth,
and just propagates it.

I don't own a pickup so I just skimmed this part, but, as an example, CR,
released today an article that shows that leaving the tailgate open on a
pickup truck, apparently, worsens gas mileage.
http://www.consumerreports.org/cro/c...nomy/index.htm
There again it depends on the truck, and speed, and a whole lot of
things (like what's in the box)

On 7/20/2017 4:59 AM, Mad Roger wrote:
On Wed, 19 Jul 2017 21:19:40 -0700,
Bob F wrote:

Maybe you can answer a question I've long wondered about.

Many cars claim in the owners manual that opening the window uses more
gas than turning on the AC. My 1987 Nissan van even claimed this, with
its almost square front and back. However, if I was going up a steep
hill in hot weather with a full load, it would slow down a lot more from
running the AC than from opening the window. Have you ever tested this
with your test rig? On what kinds of vehicles, and what did you find?
Windows or AC better?

Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
http://www.consumerreports.org/fuel-...or-ac-running/
By Consumer Reports, June 18, 2017

Q. Does a car use more gasoline when you drive with the windows rolled down
or the air conditioning turned on?

A. ´We found that on an 85-degree day, running the A/C can reduce fuel
economy by 1 to 4 mpg, depending on the car....[while] the effect of
opening the windows at 65 mph did not measurably reduce fuel economy,¡


Thanks for that article. I really didn't believe the manufacturer's
claim after the steep hill test I mentioned.

On 7/20/2017 5:58 AM, Ed Pawlowski wrote:
On 7/20/2017 7:59 AM, Mad Roger wrote:


Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
http://www.consumerreports.org/fuel-...or-ac-running/

By Consumer Reports, June 18, 2017

Q. Does a car use more gasoline when you drive with the windows rolled
down
or the air conditioning turned on?

A. ´We found that on an 85-degree day, running the A/C can reduce fuel
economy by 1 to 4 mpg, depending on the car....[while] the effect of
opening the windows at 65 mph did not measurably reduce fuel economy,¡


I'm not doubting their test results but that sounds like a broad blanket
statement. What particular car and engine? Will you get that result
with a Tesla, F-150 and 1987 Chrysler Cordova?

Both AC compressors and auto aerodynamics have improved over the years.
In any case, if it is 85 degrees, I'll have the AC on. My present car
has the best AC of any I've ever had since my first car with ac, a '68
Olds Vista Cruiser I bought in 1971.

I don't use the AC, even in hot weather.

I might be tempted, if it worked.

Here in Seattle, it really is rarely needed, especially if you take care
to park in the shade.

On Thu, 20 Jul 2017 18:14:06 -0000 (UTC), Mad Roger
wrote:

On Thu, 20 Jul 2017 08:58:28 -0400,
Ed Pawlowski wrote:

Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
http://www.consumerreports.org/fuel-...or-ac-running/
By Consumer Reports, June 18, 2017

Q. Does a car use more gasoline when you drive with the windows rolled down
or the air conditioning turned on?

A. ´We found that on an 85-degree day, running the A/C can reduce fuel
economy by 1 to 4 mpg, depending on the car....[while] the effect of
opening the windows at 65 mph did not measurably reduce fuel economy,¡


I'm not doubting their test results but that sounds like a broad blanket
statement. What particular car and engine? Will you get that result
with a Tesla, F-150 and 1987 Chrysler Cordova?

Both AC compressors and auto aerodynamics have improved over the years.
In any case, if it is 85 degrees, I'll have the AC on. My present car
has the best AC of any I've ever had since my first car with ac, a '68
Olds Vista Cruiser I bought in 1971.

That article was published *today* in the print magazine (it says), so, we
can presume they used a recent model year vehicle - but maybe more is in
the print article. (Anyone have it handy?)

The first line of the online version I quoted says they tested lots of cars
though...
"Weve tested this at various temperatures with multiple vehicles,€? says
Jake Fisher, CRs director of auto testing "

BTW, there were quite a few articles on the net which said the same thing.

So if you want to beat up the CR article, I can show you plenty more which
say the same thing that you'll also have to beat up.

BTW, most people trust their own intuition more than they trust facts to
the contrary, so you might be surprised when you read the part about what
they found out when they tested cars that SAID to use high octane fuel, but
CR tested them with the low-octane (regular) fuel instead.
http://www.consumerreports.org/cro/c...nomy/index.htm
Under some conditions, ie. high temperature,and heavy load, the 2 cars
referenced will detune due to mild detonation on regular gas. Rhis
WILL cause a (possibly small, but measurable) decrease in power output
and fuel economy. It will not show up much on thir tests, but load the
car to capacity and drive up independence pass, or any other long hard
grade and it WILL be noticeable.

The difference between "premium recommended" and "premium required"
is "premium recomended" can compensate for low octane by detuning and
not cause any damage, while "premium required" cannot compensate
enough. Under "normal" driving you may get away with regular gas on
either car

On Thu, 20 Jul 2017 15:17:56 -0700,
Bob F wrote:

Thanks for that article. I really didn't believe the manufacturer's
claim after the steep hill test I mentioned.

One problem with my older car is that the headliner and pillar-liner
material tends to flap in the wind when I use the windows.

What do you use to glue that back on anyway?

On Thu, 20 Jul 2017 18:49:56 -0400,
wrote:

BTW, most people trust their own intuition more than they trust facts to
the contrary, so you might be surprised when you read the part about what
they found out when they tested cars that SAID to use high octane fuel, but
CR tested them with the low-octane (regular) fuel instead.
http://www.consumerreports.org/cro/c...nomy/index.htm
Under some conditions, ie. high temperature,and heavy load, the 2 cars
referenced will detune due to mild detonation on regular gas. Rhis
WILL cause a (possibly small, but measurable) decrease in power output
and fuel economy. It will not show up much on thir tests, but load the
car to capacity and drive up independence pass, or any other long hard
grade and it WILL be noticeable.

The difference between "premium recommended" and "premium required"
is "premium recomended" can compensate for low octane by detuning and
not cause any damage, while "premium required" cannot compensate
enough. Under "normal" driving you may get away with regular gas on
either car

Just to let you know, my car "requires" premium (91 I believe) and yet, it
works just fine on 87 (yes, it has knock sensors so it retards the timing
"if" it knocks).

The question I've always wondered is how can I ever tell if it *did* have
to retard the timing.

I am told if I had better equipment, I *might* be able to read that out of
the ECU. All I have is OBDII stuff, so, that's beyond my capability.

On Thu, 20 Jul 2017 12:41:01 -0700 (PDT),
trader_4 wrote:

Instead of acknowledging it, you totally moved the goal posts by
dragging changing speed into it. And then you went on with more
posts, as if you never got it. I'm not sure that even now you
understand that torque and energy/work are different things.

What I care about is the answer to the question posed, which is:

What's the performance difference between 15 inch, 16 inch and 17 inch
tires (all else equal)?

And you freely joined in with Clare, when he slammed me, you thanked
him. You didn't say, "but Trader explained the physics, what about
those examples, etc?"

I'm sorry if I "freely joined" in with Clare to "slam" you, as I don't even
know whom I'm responding to. I'm just responding to what each person
writes.

So I'm responding to you right now, but I don't even know your name (nor
does it matter), so, it's not personal.

What matters is the answer to the question.

You sure changed the goal posts when I gave you the example of riding
a bicycle up hill. You then brought up wind resistance and the speed
potentially being different. Which of course it doesn't have to be,
it's just obfuscation when I was making a clear point on the physics.
You weren't talking about a car with different diameter tires, one
going 50, the other 65mph were you?

I didn't understand the physics arguments.
I was just quoting what others said.
So I shouldn't have quoted the physics forum.

I already apologized a few times for bringing up the physics forum.
I can't defend what they said because I don't know physics well enough.
I just don't.

Why would I disagree with what I and Bob F were telling
you from the start?

Fair enough.
You don't know this but I don't even look at whom I'm responding to.
I just respond to the words since I don't care who provides the answer.
I only care for the answer.

So I apologize that it appeared as if I was ganging up with the person you
call Clare to beat up on you. My response, if you read it again, I'm sure,
never once says your name because I don't think that way.

I only respond to what people say, and what Clare said is implied where I
don't blame you for inferring that I was ganging up on you with Clare.

I apologize. I was not intentionally ganging up on you.
I would have no reason for doing that.

I'd say your mistake was refusing to address the physics examples
I gave you and instead continuing on in the wilderness. And then
jumping on me with Clare, who by the way, told you the same things
that Bob F and I had.

I think I said that I don't know Physics well enough to argue that point.
I did read the articles that said the torque loss was greater with the
larger diameter wheels, but I wasn't sure why, so I didn't want to argue
what I didn't know.

I don't think the physics matters all that much because I don't think
anyone is contending that the larger diameter fitments give an inherent
advantage in fuel mileage at highway speeds anyway.

So, I think it's moot at this point, since the answer seems to be that one
would be hard pressed to gain any advantage in performance of any type
merely by simply using larger diameter fitments (except if they're lucky in
where it puts them on the torque curve).

I'm responding to the fact that it's annoying to tell you that
you were wrong, show you clear physics examples, and then you
just continue to go off in the wilderness and then join in with
Clare insulting me, when Clare is telling you the same damn thing.

I apologize for seeming to insult you.
I'm not going to re-read the posts because I know what I do, and I wasn't
intentionally responding to anything you said (although I see how you can
interpret it that way).

So I apologize that I agreed with Clare that I can tell when someone knows
what they're talking about where you thought it was me ganging up on you. I
don't disparage you for pointing out my mistake because I would have
probably inferred the same thing you inferred - based purely on the
message-id trail.

You don't know this, but 95% to 99% of the time I don't know (nor care) who
the person claims to be whom I'm responding to - since I only respond to
the words spoken.

Good grief, he we go again. The only one needing to be shot down here
was you.

Fair enough.

And yet physics is what it's all about. You had the misconception that
torque equals energy/work, it doesn't.
That was your fundamental misconception from the beginning.

I don't understand the physics well enough to figure out for my self what
happens when the diameter of the wheel/tire assembly goes up, and nothing
else changes.

Apparently, from the articles, if that puts the engine in a sweet spot,
then good things happen with respect to gas mileage. Otherwise, bad things
happen, which is most likely going to be the case given the manufacturer
knew what they were doing when they designed the vehicle with the OEM
fitment.

But you are debating physics by talking about torque and energy.

It was my fault for bringing in an article that came from a physics forum,
where I couldn't defend what the people there said because I don't know
physics well enough to defend it.

So I didn't defend the physics. I can't. I don't know enough to.

Which is what we were trying to tell you from the beginning.

Well, I don't remember who brought in articles that backed up opinions, but
the articles carried the most weight with me.

Maybe someone else did say it once, but both Bob F and I were telling you over
and over, that it isn't so. I gave you those simple physics examples.
Yet you kept saying "we intuitively think", when it was only you
that kept arguing that, post after post.

I agree with you that I had originally *thought* there was something
(anything) that was beneficial performancewise to larger fitments, where,
it turns out, that in "most cases" there is not.

If all the stars line up, then there is a single benefit of mpg at highway
cruising - which doesn't at all seem like it's worth the effort and cost.

So, in the end, larger fitments are, in reality, almost 100% for looks.
Pretty much, that answers the question posed in the op.

I did not know that then - but I know that now.
Most of you probably knew it (but some people didn't).

On Thu, 20 Jul 2017 17:37:16 -0400,
wrote:

I don't own a pickup so I just skimmed this part, but, as an example, CR,
released today an article that shows that leaving the tailgate open on a
pickup truck, apparently, worsens gas mileage.
http://www.consumerreports.org/cro/c...nomy/index.htm
There again it depends on the truck, and speed, and a whole lot of
things (like what's in the box)

I'm not going to argue because all I know is what CR said, which is...
http://www.consumerreports.org/cro/2...-gas/index.htm

"Tailgates and tonneau covers
We tested a 2013 Ram V8 on the highway at 65 mph with the tailgate up,
tailgate down, and with a factory soft tonneau cover. The tests were
performed following our usual procedure for testing highway fuel economy,
including making runs in both directions. We found that adding a tonneau
cover or lowering the tailgate hurt fuel economy, rather than helped it.

With the tailgate up and no tonneau, we got 22.3 mpg. Dropping the tailgate
decreased efficiency to 21.5 mpg. That 4-percent difference means that
driving the Ram all year exclusively on the highway could cost the owner an
extra 20 gallons of gasoline. (In reality, this big workhorse is likely to
see a mix of driving and a variety of chores, limiting the potential
penalty.) We found that covering the bed with a soft tonneau cover was even
more detrimental, dropping fuel economy to 21.4 mpg."

RAM test:
http://www.consumerreports.org/cro/n...arks/index.htm

On 07/20/2017 12:14 PM, Mad Roger wrote:
That could be the case that the EPA cares about something else (and they
can be driven by politics) - but - they must be subject to the scrutiny of
scientists at the car companies - so - we can assume they're held to a
higher standard than the mom and pop is who claims mpg figures with decimal
places.

Since MPG measurement accuracy & repeatability is a slightly different
subject from tire performance, we can take this subject over to this
thread:

If mom and pop are not taking advantage of readily available data from
the on-board computer systems they are either driving a 1972 Old Cutlass
or they are not part of the conversation. This is 2017, not 1917 when
you measured the tank level with a stick.

On Thu, 20 Jul 2017 19:56:12 -0600,
rbowman wrote:

If mom and pop are not taking advantage of readily available data from
the on-board computer systems they are either driving a 1972 Old Cutlass
or they are not part of the conversation. This is 2017, not 1917 when
you measured the tank level with a stick.

What's the accuracy & repeatability of the dashboard reading you speak of?

As you must already know, the tach isn't all that accurate on today's cars.
The temperate gauge isn't accurate on current cars either.
Neither is the speedometer (to a few percent).
Nor the fuel gauge.

Why would a purely informational dashboard mpg display be accurate?
Or repeatable?

Maybe it is - but there's no reason for it to be accurate to +/- 2% of the
indicated reading. Even the $360,000 EPA tool, as I recall, wasn't accurate
to any better than that.

What's the accuracy & repeatability of the dashboard reading you speak of?

On 07/20/2017 12:13 PM, Mad Roger wrote:
So, if you forced me at gunpoint to choose to believe something that a
Consumer Reports engineer published as fact, versus something someone on
Usenet posted as fact ... whom do you think I'd choose to save my life?

Be a toss... I haven't read the rag in a long time but years ago I was
amused by their car rating system:

inexpensive car -- a used Honda Civic is a better choice
midrange car -- A new Honda Civic is a better value
expensive car -- you could buy two Honda Civics for that

After reading the reports about items I had some knowledge about I
concluded they were going plain vanilla, middle of the road, safe bets
like the old saying 'nobody ever got fired for buying IBM'. With that in
mind I didn't really trust their recommendations about items I know
nothing about like digital cameras.

On 07/20/2017 12:14 PM, Mad Roger wrote:
Do they realize that you have to keep the *entire* test at the same
atmospheric conditions, and where the typical mom and pop doesn't do that
for an entire tank of gas (which might take a week to use up during which
time the atmospheric conditions change greatly).

While I question pop's back of an old receipt calculations, the question
isn't what the mpg would be for a known quantity of fuel at STP, but how
many real world miles were traveled with that quantity.

For example, when I was driving a truck I would often get close to 7 mpg
going east on I94 in North Dakota. Going west with the same load I would
be lucky to get 6. If you don't know why you've never been to North
Dakota. However, as far as planning my fuel stops, standard atmospheric
conditions didn't count.

On 07/20/2017 12:14 PM, Mad Roger wrote:
I don't own a pickup so I just skimmed this part, but, as an example, CR,
released today an article that shows that leaving the tailgate open on a
pickup truck, apparently, worsens gas mileage.
http://www.consumerreports.org/cro/c...nomy/index.htm

Assuming the same speed and frontal area what would be changing in the
equation is the drag coefficient. Unless you have a handy wind tunnel,
predicting the coefficient can be counter intuitive.

Back in the '30s automotive engineers were well aware of drag and its
effects.

https://en.wikipedia.org/wiki/Chrysler_Airflow

There were some beautifully sleek designs and you could even see the
after effects in the Bonneville streamliners. Then in 1938 a German
engineer by the name of Kamm made a discovery. Take a design that
smoothly transitioned into a boat tail, saw the tail off, and you had
the same Cd. You'll still see cars designed around that principle. Some
of them aren't all that pretty but they do have low drag.

https://en.wikipedia.org/wiki/Kammback

On 07/20/2017 06:14 PM, Mad Roger wrote:
On Thu, 20 Jul 2017 15:17:56 -0700,
Bob F wrote:

Thanks for that article. I really didn't believe the manufacturer's
claim after the steep hill test I mentioned.

One problem with my older car is that the headliner and pillar-liner
material tends to flap in the wind when I use the windows.

What do you use to glue that back on anyway?


Is it detached or just loose? What's the material? Steaming used to work
with fabric headliners.

On Thursday, July 20, 2017 at 10:02:01 PM UTC-4, Mad Roger wrote:
On Thu, 20 Jul 2017 19:56:12 -0600,
rbowman wrote:

If mom and pop are not taking advantage of readily available data from
the on-board computer systems they are either driving a 1972 Old Cutlass
or they are not part of the conversation. This is 2017, not 1917 when
you measured the tank level with a stick.

What's the accuracy & repeatability of the dashboard reading you speak of?

As you must already know, the tach isn't all that accurate on today's cars.


What cars? Like Bowman said, 1911 model cars? All cars today
have crankshaft position sensors that count the revolutions
with 100% accuracy. They then display it typically on an LCD
display that has enough resolution to be highly accurate.


The temperate gauge isn't accurate on current cars either.

The typical temp gauge doesn't display it with high accuracy,
if at all, but the onboard computer knows it very accurately.


Neither is the speedometer (to a few percent).

Few percent isn't good enough?


Nor the fuel gauge.

Why would a purely informational dashboard mpg display be accurate?
Or repeatable?


Maybe it is - but there's no reason for it to be accurate to +/- 2% of the
indicated reading. Even the $360,000 EPA tool, as I recall, wasn't accurate
to any better than that.

And who claimed the MPG reading had to be accurate to better than that for
it to be useful, interesting, etc.?



What's the accuracy & repeatability of the dashboard reading you speak of?

On Thu, 20 Jul 2017 20:46:08 -0600,
rbowman wrote:

Is it detached or just loose? What's the material? Steaming used to work
with fabric headliners.

The thin cloth material is detached along the c pillar for just an inch
horizontally, but about 15 inches vertically.

On Thu, 20 Jul 2017 19:50:59 -0700 (PDT),
trader_4 wrote:

Neither is the speedometer (to a few percent).

Few percent isn't good enough?

The whole point is that the calculations are off by more than people think,
so, the actual percentage matters greatly in that all the errors add up.

Speedo error adds to the fuel level error which adds to the fuel pump error
which adds to the density error which adds to the atmospheric pressure
error, etc.

All those errors add up, which is what my scientific mind sees.

I don't see mom-and-pop MPG-calculation accuracy anywhere near a decimal
point, that's for sure.

But that's why I asked the question (which is still unanswered since
references are all that matter - not opinions).

On Thu, 20 Jul 2017 20:12:09 -0600,
rbowman wrote:

After reading the reports about items I had some knowledge about I
concluded they were going plain vanilla, middle of the road, safe bets
like the old saying 'nobody ever got fired for buying IBM'. With that in
mind I didn't really trust their recommendations about items I know
nothing about like digital cameras.

I agree with you that CR does a lousy job of testing some things, e.g.,
they once tested motorcycles and rated highly the "quiet" ones, where most
bikers don't put the quietness as a critical factor.

Likewise, they measured mpg, where, again, most bikers don't really care
all that much about fuel efficiency (although tank size and miles to empty
has some bearing on the tourers).

But, still. You have to assume the engineers tested their opinions "more
better" than Joe Usenet did. You just have to assume that this is the case.

So, what CR says goes on the list, along with Car and Driver and other
hopefully reputable rags.

On 07/20/2017 08:01 PM, Mad Roger wrote:
On Thu, 20 Jul 2017 19:56:12 -0600,
rbowman wrote:

If mom and pop are not taking advantage of readily available data from
the on-board computer systems they are either driving a 1972 Old Cutlass
or they are not part of the conversation. This is 2017, not 1917 when
you measured the tank level with a stick.

What's the accuracy & repeatability of the dashboard reading you speak of?

As you must already know, the tach isn't all that accurate on today's cars.
The temperate gauge isn't accurate on current cars either.
Neither is the speedometer (to a few percent).
Nor the fuel gauge.

Why would a purely informational dashboard mpg display be accurate?
Or repeatable?

Maybe it is - but there's no reason for it to be accurate to +/- 2% of the
indicated reading. Even the $360,000 EPA tool, as I recall, wasn't accurate
to any better than that.

What's the accuracy & repeatability of the dashboard reading you speak of?


For starters, I am not talking about a dashboard display provided by the
manufacturer. As I've said repeatedly I use a ScanGauge II plugged into
the OBD II bus. How accurate and repeatable is the ECU? Tach? That would
depend on the smoothing algorithm for the display. Counting the ignition
pulses is a no brainer. Distance? The unit can be calibrated for the
rolling circumference of the tire. Variability on tire temperature and
pressure? Sure. Injector timing? Temperature? How good is the sensor?

On 07/20/2017 09:01 PM, Mad Roger wrote:
Likewise, they measured mpg, where, again, most bikers don't really care
all that much about fuel efficiency (although tank size and miles to empty
has some bearing on the tourers).

Fuel efficiency on a bike is highly variable. That's what happens when
you have a drag coefficient like a barn door. The only thing that saves
them is a low frontal area. Since I live in a state where there isn't a
gas station on every corner I tend to be interested in those matters. I
replaced the OEM tank on one bike because a potential 120-150 mile range
wasn't going to make it.


But, still. You have to assume the engineers tested their opinions "more
better" than Joe Usenet did. You just have to assume that this is the case.

I don't assume when it comes to engineers. I are one. Some are very
adept at getting data that matches their opinions.

So, what CR says goes on the list, along with Car and Driver and other
hopefully reputable rags.

C&D is an entertaining publication geared to delivering advertising to
the consumer. I have one magazine I trust -- Motorcycle Consumer News.
There is NO advertising. If they test the Vincent Super Snark and it
sucks that's what the review says. Usually there are several reviewers
riding the bike since much is subjective.

On Friday, July 21, 2017 at 10:43:26 AM UTC-4, rbowman wrote:
On 07/20/2017 09:01 PM, Mad Roger wrote:
Likewise, they measured mpg, where, again, most bikers don't really care
all that much about fuel efficiency (although tank size and miles to empty
has some bearing on the tourers).

Fuel efficiency on a bike is highly variable. That's what happens when
you have a drag coefficient like a barn door. The only thing that saves
them is a low frontal area. Since I live in a state where there isn't a
gas station on every corner I tend to be interested in those matters. I
replaced the OEM tank on one bike because a potential 120-150 mile range
wasn't going to make it.


But, still. You have to assume the engineers tested their opinions "more
better" than Joe Usenet did. You just have to assume that this is the case.

I don't assume when it comes to engineers. I are one. Some are very
adept at getting data that matches their opinions.


Engineers and scientists rely on facts and data, rather than opinions.
They may have theories, but then they test those, verify them and prove
or disprove them. And they don't rely on opinions from random internet
sites as data at all.

On Fri, 21 Jul 2017 08:35:10 -0600,
rbowman wrote:

For starters, I am not talking about a dashboard display provided by the
manufacturer. As I've said repeatedly I use a ScanGauge II plugged into
the OBD II bus. How accurate and repeatable is the ECU? Tach? That would
depend on the smoothing algorithm for the display. Counting the ignition
pulses is a no brainer. Distance? The unit can be calibrated for the
rolling circumference of the tire. Variability on tire temperature and
pressure? Sure. Injector timing? Temperature? How good is the sensor?

I think you're answering a different question than is meaningful to most
people simply because most people don't have a ScanGauge II to plug into
the OBDII port.

Most people have a tripmeter reading and a gas pumpmeter reading.
Where they fill the tank and reset the tripmeter before driving away.

I can't find any reliable source that says what the accuracy or
repeatability of that mom-and-pop tripmeter/pumpmeter calculation, but
basic logic dictates that the errors compound such that there is likely
(IMHO) no way to get anywhere near decimal-point accuracy, and worse,
probably plus or minus 1 mpg is the closest anyone can get in terms of
repeatability and precision.

So, someone's 20 mpg is really somewhere in between 19 mpg and 21 mpg.

On Fri, 21 Jul 2017 08:45:37 -0600,
rbowman wrote:

Fuel efficiency on a bike is highly variable. That's what happens when
you have a drag coefficient like a barn door.

It is amazing that even a faired motorcycle has the Cd of a semi truck!

The only thing that saves them is a low frontal area.

I would hope full fairings would help.

Since I live in a state where there isn't a
gas station on every corner I tend to be interested in those matters.

I used to get about 100 miles to a tank (give or take), no matter what bike
I had over the years (college days).

I
replaced the OEM tank on one bike because a potential 120-150 mile range
wasn't going to make it.

That's a lot more than I ever got on a tankful of fuel, at least in the
olden days.

I don't assume when it comes to engineers. I are one. Some are very
adept at getting data that matches their opinions.

I are one too.
Luckily, I don't trust my intuition.
I'd rather trust facts.

C&D is an entertaining publication geared to delivering advertising to
the consumer.

They all are, to some degree.
IMHO, C&D is better than Motor Trend, but they all get "freebies" that they
supposedly test (with the marketing guy in the passenger seat feeding them
exactly what to say).

Every rational person (and especially logical engineers and scientists),
keeps a few grains of salt with them every time someone tells them
anything.

I have one magazine I trust -- Motorcycle Consumer News.
There is NO advertising. If they test the Vincent Super Snark and it
sucks that's what the review says. Usually there are several reviewers
riding the bike since much is subjective.

You can also trust me to say it like it is (as I see it).
I will try to back up my wild-ass guesses with references (when/if I can).