Does the macadam road surface have a great effect on tire wear?
https://i.postimg.cc/KYXHVC3n/mount32.jpg

In a previous thread, we discussed tire wear on downhill slow speed (less
nominally around 30mph) steering lock to steering lock twisties due to
suspension geometries (e.g., camber scrub on the outside edge of the inside
tire due to positive caster induced from SAI+IA, with a correspondingly
confusing negative force-vector related camber on that same inside wheel).
https://i.postimg.cc/T1HkcsX5/mount31.jpg

When I mentioned that to neighbors, they told me that they considered their
high tire wear due to the road surface being not all that smooth.

The road surface happens to be not of the best quality, in that it's
certainly not "packed" as well as a highway would be, such that, even at
times, I've seen mushrooms pop up out of two inches of macadam.

If we assume the road surface isn't well packed, the question is whether
tire wear is "appreciably" affected by that road surface?

I didn't see anything in the Gillespie bible on the subject, but I didn't
read every page because my head was already spinning just by looking at the
diagrams.

Does the macadam road surface have a great effect on tire wear?

In alt.home.repair, on Tue, 25 Jun 2019 17:28:34 -0000 (UTC), "Arlen G.
Holder" wrote:

Does the macadam road surface have a great effect on tire wear?
https://i.postimg.cc/KYXHVC3n/mount32.jpg

In a previous thread, we discussed tire wear on downhill slow speed (less
nominally around 30mph) steering lock to steering lock twisties due to
suspension geometries (e.g., camber scrub on the outside edge of the inside
tire due to positive caster induced from SAI+IA, with a correspondingly
confusing negative force-vector related camber on that same inside wheel).
https://i.postimg.cc/T1HkcsX5/mount31.jpg

The one of the right front corner shows that you need a wheel alignment.



When I mentioned that to neighbors, they told me that they considered their
high tire wear due to the road surface being not all that smooth.

The road surface happens to be not of the best quality, in that it's
certainly not "packed" as well as a highway would be, such that, even at
times, I've seen mushrooms pop up out of two inches of macadam.

If we assume the road surface isn't well packed, the question is whether
tire wear is "appreciably" affected by that road surface?

I didn't see anything in the Gillespie bible on the subject, but I didn't
read every page because my head was already spinning just by looking at the
diagrams.

Does the macadam road surface have a great effect on tire wear?

On Tue, 25 Jun 2019 14:38:43 -0400, micky wrote:

The one of the right front corner shows that you need a wheel alignment.

It's my fault for showing the tires, where all I wanted to show was the
pavement. I'll snap a photo of _just_ the pavement separately, where for te
purpose of this thread, we can ignore the vehicle itself in that photo.

I understand that it _looks_ like an alignment problem in that photo, but
this happens to _many_ of the cars on this mountain, and, in particular,
this vehicle has been professionally aligned by BMW themselves so I can
only conclude that the alignment is ok.

Xeno, in another thread, showed this picture, which, I think, is really
what's happening in turns, but that's discussed elsewhe
https://www.gmforum.com/attachments/buick-172/10333d1369664321-too-much-positive-camber-after-strut-replacement-parkavenuepassengerrsidepositivecamber1.jpg

The only reason for this picture in the OP was to show the road surface.
https://i.postimg.cc/T1HkcsX5/mount31.jpg.

Please ignore the vehicle.

The thread on that specific "camber scrub" is over he
o Clare - are smaller car tires easier to balance than SUV tires?
https://groups.google.com/forum/#!topic/alt.home.repair/So4om4fLtmI

And partly here too
o How would you run a lateral acceleration test in a vehicle on twisty roads at no more than 40mph?
https://groups.google.com/forum/#!topic/comp.mobile.android/KVM5JB5M15c

Where, on turns, a specific "camber scrub" is occurring (we think):
https://i.postimg.cc/vZs6Vm3B/mount35.jpg

In contrast to that problem set, _this_ thread, is only about how much
effect the macadam road surface has on tire wear.
https://i.postimg.cc/KYXHVC3n/mount32.jpg

It is the reason for wear. If you never turned all 4 tires would wear evenly. I never turn the wheels in park. Pure friction. I only start to turn when in motion. I actually think about it.

On Tue, 25 Jun 2019 20:28:51 -0000 (UTC), "Arlen G. Holder"
wrote:

On Tue, 25 Jun 2019 14:38:43 -0400, micky wrote:

The one of the right front corner shows that you need a wheel alignment.

It's my fault for showing the tires, where all I wanted to show was the
pavement. I'll snap a photo of _just_ the pavement separately, where for te
purpose of this thread, we can ignore the vehicle itself in that photo.

I understand that it _looks_ like an alignment problem in that photo, but
this happens to _many_ of the cars on this mountain, and, in particular,
this vehicle has been professionally aligned by BMW themselves so I can
only conclude that the alignment is ok.

Xeno, in another thread, showed this picture, which, I think, is really
what's happening in turns, but that's discussed elsewhe
https://www.gmforum.com/attachments/buick-172/10333d1369664321-too-much-positive-camber-after-strut-replacement-parkavenuepassengerrsidepositivecamber1.jpg

The only reason for this picture in the OP was to show the road surface.
https://i.postimg.cc/T1HkcsX5/mount31.jpg.


Looks like pretty decent ASPHALT to me. Definitely not "Macadam" - or
tar and chip.

Please ignore the vehicle.

The thread on that specific "camber scrub" is over he
o Clare - are smaller car tires easier to balance than SUV tires?
https://groups.google.com/forum/#!topic/alt.home.repair/So4om4fLtmI

And partly here too
o How would you run a lateral acceleration test in a vehicle on twisty roads at no more than 40mph?
https://groups.google.com/forum/#!topic/comp.mobile.android/KVM5JB5M15c

Where, on turns, a specific "camber scrub" is occurring (we think):
https://i.postimg.cc/vZs6Vm3B/mount35.jpg

In contrast to that problem set, _this_ thread, is only about how much
effect the macadam road surface has on tire wear.
https://i.postimg.cc/KYXHVC3n/mount32.jpg

On 6/25/2019 5:23 PM, Clare Snyder wrote:
On Tue, 25 Jun 2019 20:28:51 -0000 (UTC), "Arlen G. Holder"
wrote:

On Tue, 25 Jun 2019 14:38:43 -0400, micky wrote:

The one of the right front corner shows that you need a wheel alignment.

It's my fault for showing the tires, where all I wanted to show was the
pavement. I'll snap a photo of _just_ the pavement separately, where for te
purpose of this thread, we can ignore the vehicle itself in that photo.

I understand that it _looks_ like an alignment problem in that photo, but
this happens to _many_ of the cars on this mountain, and, in particular,
this vehicle has been professionally aligned by BMW themselves so I can
only conclude that the alignment is ok.

Xeno, in another thread, showed this picture, which, I think, is really
what's happening in turns, but that's discussed elsewhe
https://www.gmforum.com/attachments/buick-172/10333d1369664321-too-much-positive-camber-after-strut-replacement-parkavenuepassengerrsidepositivecamber1.jpg

The only reason for this picture in the OP was to show the road surface.
https://i.postimg.cc/T1HkcsX5/mount31.jpg.


Looks like pretty decent ASPHALT to me. Definitely not "Macadam" - or
tar and chip.

Macadam is a little rougher than asphalt and more abrasive surface will
give more wear but stuff I read did not quantified amount of wear. Tire
rotation and alignment are probably much more important.

On 6/25/2019 5:36 PM, Frank wrote:
....

Macadam is a little rougher than asphalt and more abrasive surface will
give more wear but stuff I read did not quantified amount of wear. Tire
rotation and alignment are probably much more important.

And inflation and driving habits...how aggressive is the dude/dudette?

Then you get into the tire itself....

--

On Tue, 25 Jun 2019 18:36:11 -0400, Frank wrote:

Macadam is a little rougher than asphalt and more abrasive surface will
give more wear but stuff I read did not quantified amount of wear.


Thanks Frank, where I never knew there was a difference between Macadam and
asphalt.

What would you call this stuff I just showed Clare?
https://i.postimg.cc/SNJHYT9s/mount45.jpg

Tire rotation and alignment are probably much more important.

The problem is that these vehicles ALL have the same wear patterns to the
OUTSIDE edge, where a tire "rotation" won't help unless we flip the tire on
the rim, am I right?

BMW: https://i.postimg.cc/g004XCLW/mount37.jpg
Lexus: https://i.postimg.cc/8zVxVHVx/mount40.jpg
Toyota: https://i.postimg.cc/pT71cQZG/mount41.jpg

All are aligned and owned by different people, which averages out the
driving habits, wouldn't you think?

The only common factor is the road.
o Either the surface (or crown) https://i.postimg.cc/pX44ffQB/mount46.jpg
o The shape of the road https://i.postimg.cc/kGhZh80q/mount44.jpg

The main question here is what effect the road SURFACE has on this wear?

On Tue, 25 Jun 2019 14:09:54 -0700 (PDT), Thomas wrote:

It is the reason for wear. If you never turned all 4 tires would wear evenly.
I never turn the wheels in park. Pure friction.
I only start to turn when in motion. I actually think about it.

Hi Thomas,

Thanks for the advice to "not turn", which, well, which might be a little
problematic, given that this is a typical turn where the steering wheel
goes from lock to lock at a reasonably steep incline.
https://i.postimg.cc/kGhZh80q/mount44.jpg

On Tue, 25 Jun 2019 17:23:21 -0400, Clare Snyder wrote:

Looks like pretty decent ASPHALT to me.
Definitely not "Macadam" - or tar and chip.

Hi Clare,
Thanks for suggesting that where I always "assumed" macadam and Asphalt
were the "same" thing, but where you make a distinction, which I
appreciate, and where this is the overall surface at the moment:
https://i.postimg.cc/T1PF9QHt/mount43.jpg

Here's a snapshot of the "layers" that I took this morning for you:
https://i.postimg.cc/SNJHYT9s/mount45.jpg

Some people called the lower layers "chip seal", where I'm a bit confused
as to how people use the terms "asphalt" and "macadam" but I'm using it
interchangeably (our of ignorance).
https://wikidiff.com/asphalt/macadam

Nonetheless, the question is whether _this_ road surface is having any
major effect on the wear of the tires given the road is windy and steep
such that the trucks gouge many of the corners like claws scraping at the
surface.
https://i.postimg.cc/pX44ffQB/mount46.jpg

While the road surface is pretty smooth where many of the turns are almost
unnoticeable, such as this gradual almost flat curve
https://i.postimg.cc/wxf5CyS6/mount42.jpg

Some of the turns you do notice though, such as this basic hairpin:
https://i.postimg.cc/kGhZh80q/mount44.jpg

The end result of either the curves or the road, is this type of one-way
unidirectional feathering on the outside edge of the front tires:
https://i.postimg.cc/pT71cQZG/mount41.jpg

It doesn't only happen to my vehicles, as I've inspected quite a few, such
as this Lexus SUV today.
https://i.postimg.cc/G3HWPtQg/mount39.jpg

Do you think the MAJOR contributor to this Lexus SUV wear has much (if
anything) to do with the coarseness of the road surface?
https://i.postimg.cc/8zVxVHVx/mount40.jpg

It seems to be the same as this BMW SUV wear, doesn't it?
https://i.postimg.cc/g004XCLW/mount37.jpg

Both are impeccably maintained by the stealer, and both travel the same
road where, the diagnostic goal is to figure out whether the road surface
has any appreciable effect on the reputed "camber scrub" we've been
discussing.
https://i.postimg.cc/wTf1xnzJ/mount36.jpg

On Wed, 26 Jun 2019 18:19:09 -0000 (UTC), "Arlen G. Holder"
wrote:

On Tue, 25 Jun 2019 17:23:21 -0400, Clare Snyder wrote:

Looks like pretty decent ASPHALT to me.
Definitely not "Macadam" - or tar and chip.

Hi Clare,
Thanks for suggesting that where I always "assumed" macadam and Asphalt
were the "same" thing, but where you make a distinction, which I
appreciate, and where this is the overall surface at the moment:
https://i.postimg.cc/T1PF9QHt/mount43.jpg

Here's a snapshot of the "layers" that I took this morning for you:
https://i.postimg.cc/SNJHYT9s/mount45.jpg

Some people called the lower layers "chip seal", where I'm a bit confused
as to how people use the terms "asphalt" and "macadam" but I'm using it
interchangeably (our of ignorance).
https://wikidiff.com/asphalt/macadam

"Chip Seal" is Macadam

Nonetheless, the question is whether _this_ road surface is having any
major effect on the wear of the tires given the road is windy and steep
such that the trucks gouge many of the corners like claws scraping at the
surface.
https://i.postimg.cc/pX44ffQB/mount46.jpg

It would wear less on loose sand - or perhaps gravel or packed
limestone dust - but it would wash out during every rain storm. What
you have is the best compromize.

While the road surface is pretty smooth where many of the turns are almost
unnoticeable, such as this gradual almost flat curve
https://i.postimg.cc/wxf5CyS6/mount42.jpg

Some of the turns you do notice though, such as this basic hairpin:
https://i.postimg.cc/kGhZh80q/mount44.jpg

The end result of either the curves or the road, is this type of one-way
unidirectional feathering on the outside edge of the front tires:
https://i.postimg.cc/pT71cQZG/mount41.jpg

It doesn't only happen to my vehicles, as I've inspected quite a few, such
as this Lexus SUV today.
https://i.postimg.cc/G3HWPtQg/mount39.jpg

Do you think the MAJOR contributor to this Lexus SUV wear has much (if
anything) to do with the coarseness of the road surface?
https://i.postimg.cc/8zVxVHVx/mount40.jpg

It seems to be the same as this BMW SUV wear, doesn't it?
https://i.postimg.cc/g004XCLW/mount37.jpg

Both are impeccably maintained by the stealer, and both travel the same
road where, the diagnostic goal is to figure out whether the road surface
has any appreciable effect on the reputed "camber scrub" we've been
discussing.
https://i.postimg.cc/wTf1xnzJ/mount36.jpg


The car needs the alignment "customized" for the road. The ONLY thing
that will stop the problem is more negative camber on the outer wheel
through the turn. The easiest way to do that is to add negative camber
to the alignment. Changing caster can change the camber on turns too,
but adds a layer of possibly unforseen side-effects. -1 to -1.5
degrees caster added to both front wheels will reduce the wear
SIGNIFICANTLY without causing any noticeable change in handling (at
least negative changes)

On 27/6/19 7:09 am, Clare Snyder wrote:
On Wed, 26 Jun 2019 18:19:09 -0000 (UTC), "Arlen G. Holder"
wrote:

On Tue, 25 Jun 2019 17:23:21 -0400, Clare Snyder wrote:

Looks like pretty decent ASPHALT to me.
Definitely not "Macadam" - or tar and chip.

Hi Clare,
Thanks for suggesting that where I always "assumed" macadam and Asphalt
were the "same" thing, but where you make a distinction, which I
appreciate, and where this is the overall surface at the moment:
https://i.postimg.cc/T1PF9QHt/mount43.jpg

Here's a snapshot of the "layers" that I took this morning for you:
https://i.postimg.cc/SNJHYT9s/mount45.jpg

Some people called the lower layers "chip seal", where I'm a bit confused
as to how people use the terms "asphalt" and "macadam" but I'm using it
interchangeably (our of ignorance).
https://wikidiff.com/asphalt/macadam

"Chip Seal" is Macadam

Nonetheless, the question is whether _this_ road surface is having any
major effect on the wear of the tires given the road is windy and steep
such that the trucks gouge many of the corners like claws scraping at the
surface.
https://i.postimg.cc/pX44ffQB/mount46.jpg

It would wear less on loose sand - or perhaps gravel or packed
limestone dust - but it would wash out during every rain storm. What
you have is the best compromize.

While the road surface is pretty smooth where many of the turns are almost
unnoticeable, such as this gradual almost flat curve
https://i.postimg.cc/wxf5CyS6/mount42.jpg

Some of the turns you do notice though, such as this basic hairpin:
https://i.postimg.cc/kGhZh80q/mount44.jpg

The end result of either the curves or the road, is this type of one-way
unidirectional feathering on the outside edge of the front tires:
https://i.postimg.cc/pT71cQZG/mount41.jpg

It doesn't only happen to my vehicles, as I've inspected quite a few, such
as this Lexus SUV today.
https://i.postimg.cc/G3HWPtQg/mount39.jpg

Do you think the MAJOR contributor to this Lexus SUV wear has much (if
anything) to do with the coarseness of the road surface?
https://i.postimg.cc/8zVxVHVx/mount40.jpg

It seems to be the same as this BMW SUV wear, doesn't it?
https://i.postimg.cc/g004XCLW/mount37.jpg

Both are impeccably maintained by the stealer, and both travel the same
road where, the diagnostic goal is to figure out whether the road surface
has any appreciable effect on the reputed "camber scrub" we've been
discussing.
https://i.postimg.cc/wTf1xnzJ/mount36.jpg


The car needs the alignment "customized" for the road. The ONLY thing
that will stop the problem is more negative camber on the outer wheel
through the turn. The easiest way to do that is to add negative camber
to the alignment. Changing caster can change the camber on turns too,
but adds a layer of possibly unforseen side-effects. -1 to -1.5

Not if you remain within specs, as I suggested. Caster *aggravates* the
camber roll on turns. Running it down to minimum spec keeps the handling
as specified by the manufacturer.

On the other hand, if the car already has a spec of +1 to +1.5 camber,
and you reduce it by that amount, that means you have effectively no
*static* camber so steering will be guaranteed to be vague in the
straight ahead position. What's more, steering will be heavier in turns
and more liable to be affected by steering shimmy.

degrees caster added to both front wheels will reduce the wear
SIGNIFICANTLY without causing any noticeable change in handling (at
least negative changes)

That is precisely what I have been saying, drop the caster.

--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On Thu, 27 Jun 2019 14:13:38 +1000, Xeno wrote:

That is precisely what I have been saying, drop the caster.

Hi Xeno & Clare,

One thing that I shouldn't be confused about, but that I am, is that most
people I asked said they had NEGATIVE front and rear camber.

NOBODY said their static camber was positive.

Does that make sense?

Also, if you look at the road, it has a high'ish crown, given that it's
never flat even once since it's a long five miles of twisty mountain grade.
https://i.postimg.cc/pX44ffQB/mount46.jpg

It's so steep in mosts places that trucks literally run off the road or dig
INTO the road, surprisingly:
https://i.postimg.cc/pX44ffQB/mount46.jpg

Two thought questions about the CROWN of the steep twisty road:
1. How does the crown affect the customization of alignment for tire wear?
https://i.postimg.cc/wxf5CyS6/mount42.jpg
2. Is the crown part of the wear problem (we haven't mentioned it yet)?
https://i.postimg.cc/kGhZh80q/mount44.jpg

On 27/6/19 3:46 pm, Arlen G. Holder wrote:
On Thu, 27 Jun 2019 14:13:38 +1000, Xeno wrote:

That is precisely what I have been saying, drop the caster.

Hi Xeno & Clare,

One thing that I shouldn't be confused about, but that I am, is that most
people I asked said they had NEGATIVE front and rear camber.

NOBODY said their static camber was positive.

Does that make sense?

Yes. It depends on how the manufacturers set up their cars ex factory
and what they have in the specs. It has to be said too that a lot of
people wouldn't know the difference between positive and negative. Have
you looked up the actual specs for these cars? FWIW, FWD cars tend to be
a little different because they *drive* the front wheels. Also, a car
with struts is going to get less camber roll under weight
transfer/suspension jounce. Because of this, they may start at less
camber, even 0, and then have a limited movement into negative
territory. Different suspension types have different sets of compromises
and you need to look at the specs of each car in terms of suspension
type and drive arrangement.
Look at this one for example. https://i.stack.imgur.com/HnEJq.jpg

Focus on the Camry 4 cyl spec - it's -0.72, not a range, just a
preferred setting. They just give a tolerance on top of that. The
tolerance is +/- 0.75 so you could have the camber set to anywhere
between 0 and -1.5 degrees of camber, noting that the higher your static
camber goes, the more likely you are to have camber wear issues in
straight running, made worse with wider tyres. If you look at the SAI,
it is close to 12 degrees - at the top end of SAI specs. That means this
car will be less reliant on caster for self centering of the steering.
The caster settings at what appears to be 0 +/- 0.75 seems to point to
that. Certainly, at a zero setting, caster won't be doing much to
influence steering self centering and, it has to be said, won't be
worsening the effects of camber roll.

Also, if you look at the road, it has a high'ish crown, given that it's
never flat even once since it's a long five miles of twisty mountain grade.
https://i.postimg.cc/pX44ffQB/mount46.jpg

It's so steep in mosts places that trucks literally run off the road or dig
INTO the road, surprisingly:
https://i.postimg.cc/pX44ffQB/mount46.jpg

Your road is more than cambered, it's superelevated, that is, the road
has a cross slope on its full width. This not only assists drainage but
helps vehicles round the curve, the cant assisting the turning vehicle
even at slow speeds. We have a severely off cambered roundabout here
that regularly catches trucks out. Saw a tanker over on its side
recently when the driver misjudged the curve.

Two thought questions about the CROWN of the steep twisty road:
1. How does the crown affect the customization of alignment for tire wear?
https://i.postimg.cc/wxf5CyS6/mount42.jpg
2. Is the crown part of the wear problem (we haven't mentioned it yet)?
https://i.postimg.cc/kGhZh80q/mount44.jpg

You can vary the caster slightly to compensate for the crown, at least a
*normal crown*. A little more on the nearside perhaps. Roads, in this
country at least, aren't crowned like they used to be. Your pics show a
huge cant in the road to the inside of the curve which would put
pressure, at slow speeds where cornering inertia has less effect, on the
outside edge of the inside wheel which is already positively cambered to
the extreme.


--

Xeno


Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On Thu, 27 Jun 2019 19:09:03 +1000, Xeno wrote:

Yes. It depends on how the manufacturers set up their cars ex factory
and what they have in the specs. It has to be said too that a lot of
people wouldn't know the difference between positive and negative. Have
you looked up the actual specs for these cars?

Hi Xeno,

I don't know the specs, but they're all high end vehicles such as this
Lexus SUV https://i.postimg.cc/G3HWPtQg/mount39.jpg or this BMW SUV
https://i.postimg.cc/g004XCLW/mount37.jpg

FWIW, FWD cars tend to be
a little different because they *drive* the front wheels.

Very few seem to be FWD - most seem to be RWD or AWD like the X5.

Also, a car
with struts is going to get less camber roll under weight
transfer/suspension jounce. Because of this, they may start at less
camber, even 0, and then have a limited movement into negative
territory.

A few have reported high negative static camber, but, as you noted, a lot
don't know offhand what the camber is - but none who have reported have
said it was ever positive.

Different suspension types have different sets of compromises
and you need to look at the specs of each car in terms of suspension
type and drive arrangement.
Look at this one for example. https://i.stack.imgur.com/HnEJq.jpg

Notice though, that those Avalons are _all_ negative camber setups.
It doesn't seem that any cars (yet) have the Bugatti style positive camber.

Focus on the Camry 4 cyl spec - it's -0.72, not a range, just a
preferred setting. They just give a tolerance on top of that. The
tolerance is +/- 0.75 so you could have the camber set to anywhere
between 0 and -1.5 degrees of camber, noting that the higher your static
camber goes, the more likely you are to have camber wear issues in
straight running...

Notice though, that it's always negative (so far) camber, which seems to be
what I need to assume, since I'm asking for help solving a systemic problem
in hundreds of cars now that you've helped me identify the primary issue:
o Low speed camber scrub of the outside edge of the inside wheel
https://i.postimg.cc/8zVxVHVx/mount40.jpg

made worse with wider tyres.

Ah! Nobody talked about the width of the tires yet!

Are you saying that the low speed camber scrub of the outside edge of the
inside front wheel is worse with width? If so, that's one possible
amelioration, albeit there isn't much of a range that one can choose in
tires that's practicable.

If you look at the SAI,
it is close to 12 degrees - at the top end of SAI specs. That means this
car will be less reliant on caster for self centering of the steering.
The caster settings at what appears to be 0 +/- 0.75 seems to point to
that. Certainly, at a zero setting, caster won't be doing much to
influence steering self centering and, it has to be said, won't be
worsening the effects of camber roll.

I get your point that positive caster is likely the most important to
lower, where, within range, it's the most bang for the buck.

Your road is more than cambered, it's superelevated, that is, the road
has a cross slope on its full width. This not only assists drainage but
helps vehicles round the curve, the cant assisting the turning vehicle
even at slow speeds. We have a severely off cambered roundabout here
that regularly catches trucks out. Saw a tanker over on its side
recently when the driver misjudged the curve.

In general, the bigger trucks have to back up a couple of times to make
most of the curves, where in some of the curves, the trucks dig into the
roadway, as you could see in that photo.

You can vary the caster slightly to compensate for the crown, at least a
*normal crown*. A little more on the nearside perhaps. Roads, in this
country at least, aren't crowned like they used to be. Your pics show a
huge cant in the road to the inside of the curve which would put
pressure, at slow speeds where cornering inertia has less effect, on the
outside edge of the inside wheel which is already positively cambered to
the extreme.

Unfortunately, I didn't snap any photos of the width of the road, just the
corners.

It's nighttime here, so tomorrow I'll look for this "cant" in the road that
you speak of, as I'm not sure I understand what you're trying to tell me as
for its effect on the camber scrub of the tires.

CANT: https://en.wikipedia.org/wiki/Cant_%28road/rail%29
https://howlingpixel.com/i-en/Cant_%28road/rail%29
SUPERELEVATION: http://www.dailycivil.com/superelevation-of-road-advantages-design/

On Wednesday, June 26, 2019 at 2:19:13 PM UTC-4, Arlen G. Holder wrote:
On Tue, 25 Jun 2019 14:09:54 -0700 (PDT), Thomas wrote:

It is the reason for wear. If you never turned all 4 tires would wear evenly.
I never turn the wheels in park. Pure friction.
I only start to turn when in motion. I actually think about it.

Hi Thomas,

Thanks for the advice to "not turn", which, well, which might be a little
problematic, given that this is a typical turn where the steering wheel
goes from lock to lock at a reasonably steep incline.
https://i.postimg.cc/kGhZh80q/mount44.jpg

I only meant to say do not turn while parked. I bet you can wear out a new fron set in a day if you tried. Sometimes there is no choice such as when boxed in, but when not boxed in start to roll b4 turning.
Further reading allowed me to see your question better.