Help me read my tire wear

[whataboutbob]

You are understeering and/or overdriving the tire.
Checking tire temps will tell you how hot the tire is at the outside, middle, inner.
Ideally there should be about 10 degrees F spread across the tread.
You probably need more camber (to help achieve the ideal temp spread), but you also need to make sure you're not understeering and/or overdriving the tire (because camber won't solve this problem).

[andyk5]

Talked to Che Works where I had my alignment done last year, it is 2.1 front 1.6 rear.

He is against the second set of camber bolts as they don't hold the alignment well and slip. He said the issue is possibly using stock suspension and having too much body roll. Solution was 10k front rear coilovers with camber plates and rear control arms. I am not sure if I want to invest in that yet but yeah, thats where things are right now.

[Racecomp Engineering]

It's true that stock suspension, that alignment, and 200tw tires will lead to outer edge wear. But I do agree with the others that some driver mod/instruction could go a long way.

- Andrew

[whataboutbob]

Originally Posted by andyk5

Talked to Che Works where I had my alignment done last year, it is 2.1 front 1.6 rear.

He is against the second set of camber bolts as they don't hold the alignment well and slip. He said the issue is possibly using stock suspension and having too much body roll. Solution was 10k front rear coilovers with camber plates and rear control arms. I am not sure if I want to invest in that yet but yeah, thats where things are right now.

10K in the rear by itself might be too much for no aero and no Hoosiers.

Questions:
1) What tires/treadwear are you targeting for your setup?
2) Which coil overs and RCA were identified in the solution?
3) What are the adjustments available on the coil over and RCA?
4) What is the target F/R camber, caster?
5) What is the target ride height?
6) What is the target behavior of the car? (Neutral, Understeer, Oversteer)

If you don't have answers to these questions, you should probably think about what your answer would be. This will allow you to make better choices on the parts and setup.
B

[churchx]

Originally Posted by andyk5

Talked to Che Works where I had my alignment done last year, it is 2.1 front 1.6 rear.

He is against the second set of camber bolts as they don't hold the alignment well and slip. He said the issue is possibly using stock suspension and having too much body roll. Solution was 10k front rear coilovers with camber plates and rear control arms. I am not sure if I want to invest in that yet but yeah, thats where things are right now.

I have been on many trackdays with two camberbolts sets (and probably am far from being only one). Only slight issue, that with both one will get less from each then just from one, and even with both it still might slightly below optimum camber for track. Due not wishing to deal with NVH i added in addition to two camberbolt sets (SPC 81305 & Whiteline KCA416) also eccentric rubber topmounts (Pedders PED-580096) and eccentric control arm bushings (Powerflex pff69-801g). Camberplates might make it easier to reach needed optimum camber for track & using less parts (at possibly some NVH expense). Consider also getting rear LCAs to add camber adjustment there.
As starting point i'd aim for track use to -3 to -4 deg front camber (might be tire specific), and -2.5 to -3 rear camber. More neg. camber in front then rear should make grip balance less understeery (vs stock alignment, of 0dg front, -1.2 rear).
Oversteer on exit .. apart from better pedalwork, toe might help. Zero toe in front, but dial in (evenly at that between sides) some +0.1 to +0.2 rear toe-in for some self-stabilization on throttle out.
If you want to fight understeer with handling inputs, steer more with pedals then steering wheel ( - trailbraking). I often gauge my driving by aiming to steer as little as possible .
P.S. regarding camberbolt slipping .. i haven't observed much of such. But for piece of heart you can use old trick by painting white line over bolt head, to see if bolt's head has rotated. But imho torqued down to spec should hold fine.

[ZDan]

With stock suspension save for camber bolts and top hats giving you -2 front camber, excessive wear of outside front is somewhat to be expected. You really want at least -3 camber, and also stiffer springs for less roll, and lowering will further reduce roll and loading up of the outside front.

FWIW I got very good results for a street/track compromise setup on my '17 running Swift SpecR lowering springs (4.4kg/mm front, 5.3 kg/mm rear, -1.25 to -1.5") with Raceseng camber plates, first with stock PP Sachs (not nearly enough front bump travel, terrible ride harshness), then with Bilstein B8s (huge improvement!). This was a GREAT street/track setup! Might be worth a shot to get something like RCE yellows or tarmacs (-0.8") and camber plates with your GR8 stock struts, but if you go too low bump travel may become an issue...

For my '23, I went with RCE SS-2 coilovers, with the stock 7 kg/mm front springs and with 9 kg/mm rear springs replacing stock 7 kg/mm. I did this hoping for a bit better balance and cornering speed for time trials at the track. This is quite a bit stiffer than stock, but IMO still quite streetable. Definitely firmer and feels more "busy" (not harsh though) vs previous setup, but for me it's a compromise in the right direction.

I would dispute the need for RLCAs, when car is lowered, you pretty much get what you'd want for street/track rear camber (around -2.5) for free. Possibly with some asymmetry but usually not a problem. I was -2.6 to -2.8 with the old car, -2.4 to -2.6 with the new one.

For sure if you want to have fun at the track and not be burning through tires, you'll want to mod the suspension for still more front camber (at least -3), more stiffness, and lowering the car a bit will also help some. For more street-oriented though, might look more in the 4-6 kg/mm range of spring rates rather than 10.

[autoracer86]

After 5 track days(All with a co driver) on a fully stock gt86 with pilot sport 4 tires. My tires still look fine. Outer edge has some wear due to lack of camber but the wear isn't anything crazy.

I would say your tire wear is due to driving and really nothing else. You might be able to change things so the tire wears better for your driving style but you might want to change things up with your driving if you're causing this much wear to a set of tires after 4 events

[andyk5]

Originally Posted by autoracer86

After 5 track days(All with a co driver) on a fully stock gt86 with pilot sport 4 tires. My tires still look fine. Outer edge has some wear due to lack of camber but the wear isn't anything crazy.

I would say your tire wear is due to driving and really nothing else. You might be able to change things so the tire wears better for your driving style but you might want to change things up with your driving if you're causing this much wear to a set of tires after 4 events

So 5 track days with an instructor using stock tires does not apply to my situation that well as I am more in the range of 25 track days using a softer compound tire and am about 5-6 seconds off pace for fastest lap time achieved with my setup. Nothing to be proud of really however the faster you go, faster tire wears, it heats up more which makes it wear more, deform more, if it is wearing unevenly it gets exacerbated. If you want to go even faster you get in to and go beyond slip angle range where the tire sidewall folds under the wheel making things even worse. On top of that (something I learned recently) is that just upgrading tires comes with downsides like this as your suspension is too soft to handle the loads that the compound can generate.


Moral of the story if I drove the car better I could avoid some of the understeer and it would help with part of the problem but from what I am gathering in this thread is I need better suspension components if I want to make max use out of stickier tires.

[andyk5]

Originally Posted by ZDan

I would dispute the need for RLCAs, when car is lowered, you pretty much get what you'd want for street/track rear camber (around -2.5) for free. Possibly with some asymmetry but usually not a problem. I was -2.6 to -2.8 with the old car, -2.4 to -2.6 with the new one.

For more street-oriented though, might look more in the 4-6 kg/mm range of spring rates rather than 10.

Interesting, heard about camber increase due to lowering but did not know you can get -2.5ish in the rear just by lowering. How many inches are we talking about here? Also the car is 90% track, 10% drive to the track though I am trying to keep it as stock as possible.

Originally Posted by whataboutbob

10K in the rear by itself might be too much for no aero and no Hoosiers.

Questions:
1) What tires/treadwear are you targeting for your setup?
2) Which coil overs and RCA were identified in the solution?
3) What are the adjustments available on the coil over and RCA?
4) What is the target F/R camber, caster?
5) What is the target ride height?
6) What is the target behavior of the car? (Neutral, Understeer, Oversteer)

If you don't have answers to these questions, you should probably think about what your answer would be. This will allow you to make better choices on the parts and setup.
B

1-200-260, possibly big difference here but I am not that set on a specific tire.

2-I asked about this and was just given brands with respect to budget like ohlins, HKS etc... so I don't really know. As a matter of fact except adjustability options, spring rates and quality of materials I am not sure what makes a specific set of coilovers "better" than others...like this one absorbs bumps better, this one has better low speed compression (from dirt bike days)

3-See above

4-Target is -3.5 front, caster as much as possible. Rear, I don't know. Why? Well I feel like -4 is too much ( I don't see many people run it) and under 3 is not enough as -2 barely gets me half the tire. Caster ...I have read in a racing book I think that more caster always better, it centers quicker, stable etc...

5-No idea, a bit lower than what it is now but I don't want it slammed, I hit curbs, cut some apexes and don't want to rub

6-So I "FEEL" like the car is really pointy right now, as in it wants to oversteer more than understeer. However tire wear tells me a different story. I dunno, it rotates really well especially with trail braking...actually a bit too much. Maybe the oversteer that I am getting is not the car being pointy but me getting on the gas too harsh or too early.... In the end, I don't want it to handle like a Civic Type R which is maddening to me but too much oversteer is pretty hard to drive well. I'd say neutral with a slight tendency to oversteer.


In the end I think I understand the point you are making, that the "solution" is very specific to tire compound, skill/speed of the driver, desired geometry and behavior of the car. I kind of knew this which is why I have been trying to stay away from blindly "upgrading" the parts on the car, expecting them to make it better.

[marco_mc22]

You may also consider to keep it stock plus adding a pair of adjustable bars, it will be soft on squat and dive but at least you’ll have more roll resistance plus you can fine tune balance. Also, a bigger front bar does help when you’re too soft and camber limited, I have never liked bigger rear bars but it may be useful with 180Tw tires like cup2’s.

Oem ride height keeps anti-squat high, maybe too much, you can consider either a Traction Mod or a more aggressive toe alignment to keep it less oversteery on corner exit, something like 2 to 3mm open front and 1 to 2mm closed rear.

Using padders mounts, LCA bushings plus double camber bolts should get you at least 2.5 degrees, hopefully even a tad more, stock suspensions may not be super good but they’re a great compromise to me, at least my oem Showa’s (my17) were, I loved them.

PS: good camber plates are not loud, you can always invest in some good ones with oem perches with 0 to very little stack height and use your oem dampers with a proper alignment.

[autoracer86]

Originally Posted by andyk5

So 5 track days with an instructor using stock tires does not apply to my situation that well as I am more in the range of 25 track days using a softer compound tire and am about 5-6 seconds off pace for fastest lap time achieved with my setup. Nothing to be proud of really however the faster you go, faster tire wears, it heats up more which makes it wear more, deform more, if it is wearing unevenly it gets exacerbated. If you want to go even faster you get in to and go beyond slip angle range where the tire sidewall folds under the wheel making things even worse. On top of that (something I learned recently) is that just upgrading tires comes with downsides like this as your suspension is too soft to handle the loads that the compound can generate.


Moral of the story if I drove the car better I could avoid some of the understeer and it would help with part of the problem but from what I am gathering in this thread is I need better suspension components if I want to make max use out of stickier tires.

CO driver meaning a second driver. I been doing track days and auto x at a national level for years now . Also the pilot sport 4 are not a stock tire on the gt86 maybe on the newer gr86 not sure. But it's a 300tw summer tire. Its not as soft as say a A052 200tw tire but its not that hard either

I say its your driving not the suspension but can't hurt to get more camber

[andyk5]

Originally Posted by autoracer86

CO driver meaning a second driver. I been doing track days and auto x at a national level for years now . Also the pilot sport 4 are not a stock tire on the gt86 maybe on the newer gr86 not sure. But it's a 300tw summer tire. Its not as soft as say a A052 200tw tire but its not that hard either

I say its your driving not the suspension but can't hurt to get more camber

Pilot Sport 4 is stock on GR premium yes. Also with GT Radial SX2's (I think 260 TW A A) this issue does not happen without modifying my driving style.

I am not saying driving is not the issue btw, there is a lot of room for improvement there for sure.

[ZDan]

Originally Posted by andyk5

Interesting, heard about camber increase due to lowering but did not know you can get -2.5ish in the rear just by lowering. How many inches are we talking about here?

My cars, -30 to -35mm lower than stock to get -2.5 or a bit more negative camber.

4-Target is -3.5 front, caster as much as possible. Rear, I don't know. Why? Well I feel like -4 is too much ( I don't see many people run it) and under 3 is not enough as -2 barely gets me half the tire. Caster ...I have read in a racing book I think that more caster always better, it centers quicker, stable etc...

-2.5 is IMO "enough" rear camber for track usage. Front camber more important anyway. -3.5 is a good target there.
As for caster, some seem to think more is always better, but I'm a fan of minimal caster. IMO caster can add weight while *detracting* from feel. Personally I don't want or need more "self-centering". I kind of like the steering to feel more "free", and I think excessive caster and "weight" can take away from your ability to feel subtle changes in slip/grip vs. steering input. My 0.02...

6-So I "FEEL" like the car is really pointy right now, as in it wants to oversteer more than understeer. However tire wear tells me a different story. I dunno, it rotates really well especially with trail braking...actually a bit too much. Maybe the oversteer that I am getting is not the car being pointy but me getting on the gas too harsh or too early....

Car pointing in and rotating well with trail-braking is useful. Shouldn't be getting much if any oversteer getting on the gas except maybe in the slowest 2nd gear corners. Even then, if proper apex and unwinding the steering to track-out, I don't think you should be seeing much/any oversteer getting decently hard on the gas on most corner exits.

[churchx]

Originally Posted by ZDan

As for caster, some seem to think more is always better, but I'm a fan of minimal caster. IMO caster can add weight while *detracting* from feel. Personally I don't want or need more "self-centering". I kind of like the steering to feel more "free", and I think excessive caster and "weight" can take away from your ability to feel subtle changes in slip/grip vs. steering input. My 0.02...

Another drawback of excessive caster and thus more overworked power steering may overheat it on earlier twins (if paired with grippier tires) resulting it switching off sometimes.