On 07/19/2017 12:00 AM, Mad Roger wrote:
What's the *performance* difference between 15 inch, 16 inch and 17 inch
tires (all else being equal)?

Let's say that the stock wheel is 16 inch and let's ignore sheer looks, and
the fact the speedometer will read differently, and let's ignore obvious
non-performance wheel-well fitment issue since they're obviously not
performance changes.

What *performance* changes will the one inch larger or smaller tire cause?

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

The psychological problem I'm having with "bling" with respect to race cars
is that there seem to be zero performance benefits of larger wheels, even
for race cars.

What race car benefits from 25% less torque at the driving wheel contact
patch for example?

On 7/19/2017 10:50 AM, Mad Roger wrote:
On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

The psychological problem I'm having with "bling" with respect to race cars
is that there seem to be zero performance benefits of larger wheels, even
for race cars.

What race car benefits from 25% less torque at the driving wheel contact
patch for example?


They change the gear ratio, eliminating the difference. Jeeeze!

And that 25% difference is going from a 15" to a 19" wheel, and
similarly larger tire diameter. Who does that without changing the gearing?

On Wed, 19 Jul 2017 11:28:11 -0700,
Bob F wrote:

They change the gear ratio, eliminating the difference. Jeeeze!

And that 25% difference is going from a 15" to a 19" wheel, and
similarly larger tire diameter. Who does that without changing the gearing?

Thank you for pointing out my error of the 25% loss in torque being from
only a 1 inch change.

I misinterpreted the Ed Pawlowski article.
https://www.carthrottle.com/post/how...t-performance/

The 25% loss of torque came with a four inch change in diameter!

But it's still a loss in torque.
The Car and Driver article said the fuel mileage suffered also.

Effects of Upsized Wheels and Tires Tested
http://www.caranddriver.com/features...d-tires-tested

"What's immediately apparent from the results is that as the wheel-and-tire
packages get larger and heavier, acceleration and fuel economy suffer.
Neither is a huge surprise, but we measured a 10-percent drop in fuel
economy and a four-percent degradation in 0-to-60-mph acceleration from the
15s to the 19s"

On 7/19/2017 12:18 PM, Mad Roger wrote:
On Wed, 19 Jul 2017 11:28:11 -0700,
Bob F wrote:

They change the gear ratio, eliminating the difference. Jeeeze!

And that 25% difference is going from a 15" to a 19" wheel, and
similarly larger tire diameter. Who does that without changing the gearing?

Thank you for pointing out my error of the 25% loss in torque being from
only a 1 inch change.

I misinterpreted the Ed Pawlowski article.
https://www.carthrottle.com/post/how...t-performance/

The 25% loss of torque came with a four inch change in diameter!

But it's still a loss in torque.
The Car and Driver article said the fuel mileage suffered also.

Effects of Upsized Wheels and Tires Tested
http://www.caranddriver.com/features...d-tires-tested

"What's immediately apparent from the results is that as the wheel-and-tire
packages get larger and heavier, acceleration and fuel economy suffer.
Neither is a huge surprise, but we measured a 10-percent drop in fuel
economy and a four-percent degradation in 0-to-60-mph acceleration from the
15s to the 19s"


But of course, that fuel economy was based on odometer readings, which
are reading 26% low with the 19" tires. And the acceleration was only
slightly different because only the 1st gear part of the acceleration is
going to be changed much. After that, the gears keep the engine near
it's optimal power range for acceleration. On the highway, the engine
will be operating at 26% lower RPM, so depending on the power curve of
the engine, mileage could go either way.

On Wednesday, July 19, 2017 at 3:58:17 PM UTC-4, Bob F wrote:
On 7/19/2017 12:18 PM, Mad Roger wrote:
On Wed, 19 Jul 2017 11:28:11 -0700,
Bob F wrote:

They change the gear ratio, eliminating the difference. Jeeeze!

And that 25% difference is going from a 15" to a 19" wheel, and
similarly larger tire diameter. Who does that without changing the gearing?

Thank you for pointing out my error of the 25% loss in torque being from
only a 1 inch change.

I misinterpreted the Ed Pawlowski article.
https://www.carthrottle.com/post/how...t-performance/

The 25% loss of torque came with a four inch change in diameter!

But it's still a loss in torque.
The Car and Driver article said the fuel mileage suffered also.

Effects of Upsized Wheels and Tires Tested
http://www.caranddriver.com/features...d-tires-tested

"What's immediately apparent from the results is that as the wheel-and-tire
packages get larger and heavier, acceleration and fuel economy suffer.
Neither is a huge surprise, but we measured a 10-percent drop in fuel
economy and a four-percent degradation in 0-to-60-mph acceleration from the
15s to the 19s"


But of course, that fuel economy was based on odometer readings, which
are reading 26% low with the 19" tires.

I would give Car and Driver credit for accounting for that in their
testing. What;s also interesting is that they made a 4" change in
diameter and saw only a 4% decrease in acceleration, which is very
different than what was claimed in that other article, where there
was huge alleged difference in acceleration with just a 1" change.

On Wed, 19 Jul 2017 12:53:25 -0700, Bob F wrote:

On 7/19/2017 12:18 PM, Mad Roger wrote:
On Wed, 19 Jul 2017 11:28:11 -0700,
Bob F wrote:

They change the gear ratio, eliminating the difference. Jeeeze!

And that 25% difference is going from a 15" to a 19" wheel, and
similarly larger tire diameter. Who does that without changing the gearing?

Thank you for pointing out my error of the 25% loss in torque being from
only a 1 inch change.

I misinterpreted the Ed Pawlowski article.
https://www.carthrottle.com/post/how...t-performance/

The 25% loss of torque came with a four inch change in diameter!

But it's still a loss in torque.
The Car and Driver article said the fuel mileage suffered also.

Effects of Upsized Wheels and Tires Tested
http://www.caranddriver.com/features...d-tires-tested

"What's immediately apparent from the results is that as the wheel-and-tire
packages get larger and heavier, acceleration and fuel economy suffer.
Neither is a huge surprise, but we measured a 10-percent drop in fuel
economy and a four-percent degradation in 0-to-60-mph acceleration from the
15s to the 19s"


But of course, that fuel economy was based on odometer readings, which
are reading 26% low with the 19" tires. And the acceleration was only
slightly different because only the 1st gear part of the acceleration is
going to be changed much. After that, the gears keep the engine near
it's optimal power range for acceleration. On the highway, the engine
will be operating at 26% lower RPM, so depending on the power curve of
the engine, mileage could go either way.
I REALLY doubt it was "uncorrected" data, and the shiftpoints need
to be reprogrammed (if it is an automatic) or shift points changed by
the driver to optimize either mileage or accelleration. It is NOT a
simple calculation to determine which way mileage will go, or how to
drive the modified vehicle for best results.

On Wed, 19 Jul 2017 12:53:25 -0700,
Bob F wrote:

But of course, that fuel economy was based on odometer readings, which
are reading 26% low with the 19" tires. And the acceleration was only
slightly different because only the 1st gear part of the acceleration is
going to be changed much. After that, the gears keep the engine near
it's optimal power range for acceleration. On the highway, the engine
will be operating at 26% lower RPM, so depending on the power curve of
the engine, mileage could go either way.

Even worse, it could be argued that "standard methods" of calculating mpg
are off by a factor of about a mile per gallon either way, which means
that, say, 20mph is anywhere from 19mpg to 21mpg.

Certainly anyone who calculates mpg with decimal places is ignoring sig
figs in their measurement capabilities in that nobody does a reliable test
loop (and even those who do, in Austin Texas for example, get sig figs not
much better than that).

WARNING: I have to look up if challenged the actual reliability but I
"assume" that most people think their measurements are infinitely more
accurate and repeatable than they really are. If it's not as big as +1 and
-1 mpg accuracy, it's not that far off. Certainly there is no decimal place
in typical mpg calculations by a consumer.

On 07/19/2017 01:53 PM, Bob F wrote:

But of course, that fuel economy was based on odometer readings, which
are reading 26% low with the 19" tires.

That would be a real half-assed test. It's not rocket science. Japanese
bikes are notoriously inaccurate for both speed and odometer so I use a
GPS. Harley's, strange to say, tend to be quite accurate. Unfortunately
the LED display on mine is getting hard to read unless it's hot out so I
use a $20 Sigma bicycle computer. Measure the rolling circumference of
the tire, program the computer, check it with a GPS, and you're good to go.

On Wed, 19 Jul 2017 11:28:11 -0700, Bob F wrote:

On 7/19/2017 10:50 AM, Mad Roger wrote:
On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

The psychological problem I'm having with "bling" with respect to race cars
is that there seem to be zero performance benefits of larger wheels, even
for race cars.

What race car benefits from 25% less torque at the driving wheel contact
patch for example?


They change the gear ratio, eliminating the difference. Jeeeze!

And that 25% difference is going from a 15" to a 19" wheel, and
similarly larger tire diameter. Who does that without changing the gearing?
"tuner kids"

On 07/19/2017 11:50 AM, Mad Roger wrote:
The psychological problem I'm having with "bling" with respect to race cars
is that there seem to be zero performance benefits of larger wheels, even
for race cars.

Bling and performance have no correlation. Race cars generally have to
meet specifications. For example NASCAR calls for 15" steel wheels. F1
is even more restrictive. The wheels RE 13" and all tires are supplied
by Pirelli. Pirelli has several different models based on stiffness,
wet/ dry, and so forth but they're all Pirelli. At one time Bridgestone
was in but they were dropped. I don't know why. IndyCars run Firestone
on 15" wheels.

I'm curious what race cars run 17/18/19" wheels.

On Wed, 19 Jul 2017 17:50:17 -0000 (UTC), Mad Roger
wrote:

On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

The psychological problem I'm having with "bling" with respect to race cars
is that there seem to be zero performance benefits of larger wheels, even
for race cars.

What race car benefits from 25% less torque at the driving wheel contact
patch for example?
When it has 1000 plus horsepower to the rear wheels, that decrease in
torque CAN mean he doesn't burn the tires off as easily - and on a
drag car, the tire diameter can be adjusted to get the car to launch
better, and to top out it's speed at the right point on the track

rbowman posted for all of us...



On 07/19/2017 12:00 AM, Mad Roger wrote:
What's the *performance* difference between 15 inch, 16 inch and 17 inch
tires (all else being equal)?

Let's say that the stock wheel is 16 inch and let's ignore sheer looks, and
the fact the speedometer will read differently, and let's ignore obvious
non-performance wheel-well fitment issue since they're obviously not
performance changes.

What *performance* changes will the one inch larger or smaller tire cause?

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

I think this guy is the same argumentative/troll about weight weights and
Horror fright bead breakers, etc. He just changed hosts.

--
Tekkie

On Wednesday, July 19, 2017 at 3:19:01 PM UTC-4, Tekkie® wrote:
rbowman posted for all of us...



On 07/19/2017 12:00 AM, Mad Roger wrote:
What's the *performance* difference between 15 inch, 16 inch and 17 inch
tires (all else being equal)?

Let's say that the stock wheel is 16 inch and let's ignore sheer looks, and
the fact the speedometer will read differently, and let's ignore obvious
non-performance wheel-well fitment issue since they're obviously not
performance changes.

What *performance* changes will the one inch larger or smaller tire cause?

Basically, I'm wondering why people almost universally want larger wheels,
where all I'm asking about are what the performance tradeoffs are.


Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

I think this guy is the same argumentative/troll about weight weights and
Horror fright bead breakers, etc. He just changed hosts.

--
Tekkie

Stifle yourself! I made one sarcastic remark to the poster, after about
6 exchanges where he's going in circles, and I was accused of being nasty
to everyone on the internet!

On Wed, 19 Jul 2017 13:57:54 -0700 (PDT), trader_4
wrote:


I think this guy is the same argumentative/troll about weight weights and
Horror fright bead breakers, etc. He just changed hosts.

--
Tekkie

Stifle yourself! I made one sarcastic remark to the poster, after about
6 exchanges where he's going in circles, and I was accused of being nasty
to everyone on the internet!

Not the Internet son, "Usenet". Do you not know the difference?

On Wed, 19 Jul 2017 13:57:54 -0700 (PDT), trader_4
wrote:

Stifle yourself!

ROFL - "Stifle", who dug up Carroll O'Connor and gave him access to
Usenet?

"Stifle yourself Edith, dummy up"

- Carroll O'Connor as Archie Bunker, All in the Family, 1971 - 1979

On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

I searched for that thread.

Is it this one?
Why 20" wheels, by Micky, May 8, 2017
https://groups.google.com/forum/#!to...ZxvM%5B1-25%5D

If so, I'll read it to see if there was more accurate information there
than here.

On Thu, 20 Jul 2017 02:13:30 -0000 (UTC), Mad Roger
wrote:

On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

I searched for that thread.

Is it this one?
Why 20" wheels, by Micky, May 8, 2017
https://groups.google.com/forum/#!to...ZxvM%5B1-25%5D

If so, I'll read it to see if there was more accurate information there
than here.
Nothing of value there.

On 07/19/2017 08:13 PM, Mad Roger wrote:
On Wed, 19 Jul 2017 11:06:54 -0600,
rbowman wrote:

Bling. This topic was beaten to death a month or two ago. When someone
says larger diameter wheels must be effective because they are used on
race cars ask them what size wheels are mandated for F1 or NASCAR and
what sort of racing they had in mind outside of the Fast & Furious
franchise.

I searched for that thread.

Is it this one?
Why 20" wheels, by Micky, May 8, 2017
https://groups.google.com/forum/#!to...ZxvM%5B1-25%5D

If so, I'll read it to see if there was more accurate information there
than here.


Don't bother. There was more bull**** in that thread than in a feedlot.

On Wed, 19 Jul 2017 23:08:20 -0600,
rbowman wrote:

I searched for that thread.

Is it this one?
Why 20" wheels, by Micky, May 8, 2017
https://groups.google.com/forum/#!to...ZxvM%5B1-25%5D

If so, I'll read it to see if there was more accurate information there
than here.


Don't bother. There was more bull**** in that thread than in a feedlot.

Thanks. By now you can tell that I care about two things:
+ I have an "opinion" about everything, but I don't trust my opinion, so,
+ I try to get facts that either support or contradict that opinion.
If those facts are reliable, I change my opinion.

My original opinion was that there was a performance benefit to
larger-diameter fitments, but my new opinion is based on the facts
unearthed in this thread, which is that you'd be hard pressed to gain the
one known performance advantage, which is to put the engine into a sweeter
spot on the torque curve.

However, even if you did that, there are many other factors, the
next-biggest of which is the contact patch, but there are others such as
the weight change, materials change, suspension change, etc.

Hence, larger fitments have, essentially, no performance advantage and most
likely have a negative effect on performance overall in most cases.

If anyone has data that contradicts that opinion, I'm all ears.

On 07/20/2017 05:59 AM, Mad Roger wrote:
Hence, larger fitments have, essentially, no performance advantage and most
likely have a negative effect on performance overall in most cases.

But they look kewl... There is a similar phenomenon with motorcycles.
The first thing many Harley owners do is replace the stock exhaust with
aftermarket pipes. While they've gotten better at hiding it, the OEM
exhaust has a cross over between the two pipes that people find
unappealing. The new pipes may have less restriction and be louder. They
may be shinier. In most cases they also result in a slight reduction in
power. Most of the people aren't doing baseline dyno runs and retesting
after modifications. They are buying bling and working on the intuition
that more noise == less back pressure == more power.

On Thu, 20 Jul 2017 09:02:15 -0600,
rbowman wrote:

Hence, larger fitments have, essentially, no performance advantage and most
likely have a negative effect on performance overall in most cases.

But they look kewl...

Yup. We agree.

Putting an M3 badge on an otherwise 3-series bimmer makes it look faster
too!

And, whitewall tires look kewl to some, where nobody thinks that there's an
inherent performance benefit (I hope!).

There is a similar phenomenon with motorcycles.
The first thing many Harley owners do is replace the stock exhaust with
aftermarket pipes. While they've gotten better at hiding it, the OEM
exhaust has a cross over between the two pipes that people find
unappealing. ]

Interesting.
The whole point of exhaust pipes on a motorcycle are, I would assume
+ Get the hot gas out the bike without burning the rider (or the bike)
+ Get it out fast without hindering the engine HP to push it out
+ Keep the sound to a "sane" level (as determined by all within earshot)
+ Look ok to the buyer of the bike (e.g., shiny things look good to fish)

My problem with bike "sounds" is that the potato-potato-potato sound isn't
so much an issue with me as is the presumably child-like psychology of
someone whose pipes are unreasonably loud.

Why?
Do they need attention *that* badly and can't get it any way else?

Please note that I am not a psychologist so take my quick psychoanalysis of
the loud-pipe crowd with a grain of salt and some humor.

The new pipes may have less restriction and be louder. They
may be shinier. In most cases they also result in a slight reduction in
power. Most of the people aren't doing baseline dyno runs and retesting
after modifications. They are buying bling and working on the intuition
that more noise == less back pressure == more power.

Understood completely.
It's sad, but loud pipes exist, so, there must be a *lot* of people working
on those same (probably scientifically flawed) assumptions.

In a very real way, the loud pipes = more power argument stands on the same
fundamentals that the bigger wheels = more performance argument.

Sure, you can get it - but you'd be hard pressed to beat the manufacturer
in most cases, and even if you did - there are almost always engineering
(aka scientific) cons for every pro.

For example, why not just get rid of the pipes altogether?
Then you'd have the least resistance (although no tuning) of the air
outflow from the engine.

I guess the argument is that would be too loud (but some pipes I hear
riding past my house, which is on a busy street, seem *that* loud!).