Help figure out this uneven tire wear.

[Yoshoobaroo]

Originally Posted by Irace86.2.0

I’ll make an appointment for an alignment then report back.

Tire pressure is usually 38-42 in front and 34-38 in rear. It never is higher unless the tires are getting hot. Typically it is lower.

Sounds high. With wider tires you want less pressure than stock.

[Westen86]

245/40-17 tires I run at 28-30lbs on the street.

[ZDan]

Street driven street car, even wear just means you don't have nearly enough negative camber! The asymmetric wear I'm seeing doesn't look that bad really. Better to have some inside wear and much greater cornering grip. Perfectly even tire wear is way way way overrated. Again, IMO... If you wanna even the wear out do some track days

[86MLR]

Needs less camber and/or less toe.

On a nice dry day put a chalk mark across the wear surface and drive your route to work, then look for where the chalk isn't worn off.

Do the same thing on the return journey.

When you mark the tyre make sure you take the chalk all the way to where the tread finishes and the sidewall starts.

This is a fairly rough way to check camber, but it lets you know if you are using the whole tread surface.

Also get some form of solution for tweeking your camber, the cost is offset by not scrubbing out your tyres prematurely.

For my street cars I always set 0 toe.

Opinions may vary

[Yoshoobaroo]

Originally Posted by Westen86

245/40-17 tires I run at 28-30lbs on the street.

A good formula to baseline your pressure:

tire pressure = stock pressure x stock tire width / new tire width

That will get you the same area contact patch. It’s not exact, but it is a good baseline to start. You can adjust pressure if you see the center wearing too much/not enough. The chalk mark is a great idea for that.

[Irace86.2.0]

Originally Posted by Yoshoobaroo

Sounds high. With wider tires you want less pressure than stock.

That doesn't sound right. Are you sure? When volume greatly increases then pressure can drop, yet even that isn't a given, but I didn't think the width was as important as the side wall thickness. Typically as the side wall thickness decreases, tire pressure should be increased, so that a bump or high speed corner doesn't lead to a bent or cracked rim. The recommended pressure is 35 psi all around, but on the TRD edition they show 38 psi on the fronts. I don't know if this is because the side wall is thinner by 0.4'', or if they believe those cars will see more performance, such that, high load from high braking might require more psi.



Regardless, my tire wear may not look it from the pictures, but it is wedge shaped, meaning, there isn't excessive center wear like one might expect on over-inflated tires. I double checked right now because it has been a while, and my fronts were 36 psi and 37 psi and my rears were both 34 psi. My side wall thickness is 0.1'' smaller than stock, so I don't need to make adjustments there. I mostly ran at the top of the range because I'm lazy about topping up tire pressure.

I made an appointment with the local Les Schwab to get an alignment. I don't know if there is a difference between getting measurements taken and getting adjustments made. I guess I will find out.

[Yoshoobaroo]

Volume isn’t relevant here, since you set the pressure to what you want. It’s the shape of the contact patch that matters. Your contact patch doesn’t change length easily (for a given diameter), it’s much easier for the contact patch to change width. So when you add pressure you make the patch less wide, if you drop the pressure you widen it. When you put wider tires on you won’t have much of a change in the length of the patch, and the area is set by the pressure (weight of car/4 /pressure = contact patch area). That means the pressure has a direct effect on the contact patch width.

[ZDan]

I wouldn't assume wider means you should run lower pressure, and for sure I wouldn't go by a chalk mark to determine optimal pressures for radial tires on the street or at the track.

32-35psi is gonna be just fine whether you're on 215s or 255s. 30psi isn't going to be a problem but IMO no real benefit on the street. At the track you'd have to log a ton of laps to optimize but I generally just aim for ~35psi hot. Some seem to try to see how low they can go but if you're near optimal pressure there shouldn't be much performance drop on either side, and it's more conservative to run higher than lower.

0.02...

[soundman98]

Originally Posted by Irace86.2.0

The tires have 30-35k miles on them. Mounted during March of 2016.

wow! i'm at 38k total milage, and looking for my 3rd set of tires... i'd say you got some pretty great wear out of this set!

Originally Posted by Irace86.2.0

Just in case the pictures aren't clear. The rears have inside wear. They aren't horrible, but the outsides look much newer than the insides, and the right rear is slightly worse than the left rear. The fronts are worse. The inside versus outside wear ratio on the right front looks pretty bad like it will need replacing soon, yet oddly, the left front looks pretty good in overall wear and in the difference between the inside and outside of the tire. Again, it seems odd that the front has a one tire in the best shape and one tire in the worst shape.

i'd say that with the suspension modifications, you gave yourself a roughly 1-in-4 chance of getting the alignment settings close. i'd say the right front is way out, and the rear have some camber issues. both rear tires are exhibiting signs of overinflation, my guess is close to 10psi over, 5 tends to be only 1/32nd difference, that looks closer to 3/32 difference in tread.

Originally Posted by Irace86.2.0

I never had an alignment, so I suppose I could start there, but I'm not entirely sure if a proper alignment can be done on tires that have uneven wear. Can it? I considered having the tires swapped right to left by having them remounted and rebalanced, which will cost about $160 and could be done because the tires aren't asymmetric. I don't know if this is worth the money, or if I should just drive until I need new tires. What do you think?

alignments are done by mounting the sensors to the wheels, not the tires. if your wheels are out of true, you'd be having a dramatically different issue with vibration and vehicle controllability.

at this point, those tires are done. an alignment is your next best step, part of the preparation for the next set of tires to minimize them from getting the same wear pattern.

swapping the tires from side to side is something that is generally recommended every other oil change, same as typical tire rotation. in this vehicles case, that would be at 15k miles.

Originally Posted by Irace86.2.0

Everyone is going to have a different opinion on what alignment settings I should have from those that like a stanced/camber look to guys that are going to get on my case for not having a square setup because square is the best for the track.

i've never heard anyone say that a square setup is best for the track. no, the primary benefit to a square setup is that you can then rotate the tires to all 4 corners, which will subject all 4 tires to the same wear pattern, averaging it all out. square setups are the best for standard driving if you prefer to prioritize wear over performance.

a non-square setup can be more aesthetically pleasing, and also offer better grip characteristics in certain aspects--many higher performance cars use a non-square setup to minimize the rear from swapping ends, and aid rwd platforms to get the power to the road. but the major downside is tire rotation is harder-- you can only go side-to-side instead of opposing corners, which will wear the tires faster, and usually more unevenly. i recall reading of this issue in the sunday paper 15-20 years ago from new corvette owners.
now that forums and facebook exist, i imagine you could find a dozen threads/posts now with the same issue.

every decision has a compromise.

[Yoshoobaroo]

Originally Posted by soundman98

wow! i'm at 38k total milage, and looking for my 3rd set of tires... i'd say you got some pretty great wear out of this set!




i'd say that with the suspension modifications, you gave yourself a roughly 1-in-4 chance of getting the alignment settings close. i'd say the right front is way out, and the rear have some camber issues. both rear tires are exhibiting signs of overinflation, my guess is close to 10psi over, 5 tends to be only 1/32nd difference, that looks closer to 3/32 difference in tread.



alignments are done by mounting the sensors to the wheels, not the tires. if your wheels are out of true, you'd be having a dramatically different issue with vibration and vehicle controllability.

at this point, those tires are done. an alignment is your next best step, part of the preparation for the next set of tires to minimize them from getting the same wear pattern.

swapping the tires from side to side is something that is generally recommended every other oil change, same as typical tire rotation. in this vehicles case, that would be at 15k miles.



i've never heard anyone say that a square setup is best for the track. no, the primary benefit to a square setup is that you can then rotate the tires to all 4 corners, which will subject all 4 tires to the same wear pattern, averaging it all out. square setups are the best for standard driving if you prefer to prioritize wear over performance.

a non-square setup can be more aesthetically pleasing, and also offer better grip characteristics in certain aspects--many higher performance cars use a non-square setup to minimize the rear from swapping ends, and aid rwd platforms to get the power to the road. but the major downside is tire rotation is harder-- you can only go side-to-side instead of opposing corners, which will wear the tires faster, and usually more unevenly. i recall reading of this issue in the sunday paper 15-20 years ago from new corvette owners.
now that forums and facebook exist, i imagine you could find a dozen threads/posts now with the same issue.

every decision has a compromise.

A square setup is ABSOLUTELY better for the track. It makes the car far more willing to rotate. This is really common knowledge in the car community AFAIK.

[soundman98]

Originally Posted by Yoshoobaroo

A square setup is ABSOLUTELY better for the track. It makes the car far more willing to rotate. This is really common knowledge in the cat community AFAIK.

well i don't own a cat. i bought a car. that would explain why i don't know about it.

[Decep]

Obviously, check the alignment.

I have -2.5 degrees front camber and 0 degree toe, and i had some inside wear when i had to replace my MPSS after about 20k miles (verified the alignment at my usual shop after i got new tires). It was only apparent towards the very end of their life. Don't believe people saying only toe in/out is what kills tires.

ALSO. You have 30+k miles on higher performance summer tires...they're probably heat cycled anyways, and the tread is done even on the "good side."

[Yoshoobaroo]

Originally Posted by soundman98

well i don't own a cat. i bought a car. that would explain why i don't know about it.

[Irace86.2.0]

Originally Posted by Yoshoobaroo

Volume isn’t relevant here, since you set the pressure to what you want. It’s the shape of the contact patch that matters. Your contact patch doesn’t change length easily (for a given diameter), it’s much easier for the contact patch to change width. So when you add pressure you make the patch less wide, if you drop the pressure you widen it. When you put wider tires on you won’t have much of a change in the length of the patch, and the area is set by the pressure (weight of car/4 /pressure = contact patch area). That means the pressure has a direct effect on the contact patch width.

None of the tires show center wear. It is progressive from the inside out.