[M12LRV]

So this will be my second season autocrossing. With the stock setup, last season I was wearing out mostly the outer 20% of my PS4S tires (285 front 305 rear) with SS 1LE replica wheels doing autocross. This season I got a track alignment, with -1.9 degrees camber in front and -1.5 in the rear (best the Chevy dealer could get), and also installed the Hotchkis front and BMR rear sway bars, with both set to the middle stiffness. With this setup I'm wearing mostly the outer 40-50% of my new PS4S tires.

Any recommendations on how to get more even wear and better contact patch when cornering?

I was thinking of setting the sway bars to full stiffness but not sure how this will affect drivability, as this is still my daily driver. I'm also planning on taking my car to Jannetty Performance this summer when I'm in town to see if they can improve the camber (I have already taken it to two shops for alignment). I'm also going to get 19" APEX wheels with a square 305 Falken AZENIS RT660 for autocross. I don't want to mess with springs as my MRC dampers on my 2016 SS are not tunable. Thanks

[Og Neon]

You need way more front camber than 1.9. Bump it up to 3 and that will help. At 1.9 you are going to kill your outside edges. Also the stiffer front bars will put more load on the tires which will further increase that wear you are seeing if you aren't aligned right. I have a ZLE and autocross heavily, my setup is -3f/1.7r and i see pretty even wear across multiple tires (PS4S, 660s, RE71s). Hopefully someone else chimes in soon because I thought you could go higher then 1.9 in the SS. Maybe camber plates need to be your next purchase.

[VR Baron]

Find a good alignment shop. At least on our ss 1le’s we can get -2.5 front camber. Your rear camber is fine as to wear, and you have huge sway bars. 1le size sway bars would be enough depending on the car balance you like. And as said the big bars set middle maybe overworking those tires.I would think the other main issue would be the tires. Mps4s have a softer sidewall from what I read on this forum, why people get them for better ride quality. Better to get Goodyear’s sc3 that come on the 1le. And in 20” size, about the best you will get for handling.
If you are going 19” then more tire choices.

Edit: also make sure your hot psi is 35-36. Michelin’s liked that when I used them on my fifth gen to autocross with a stiff suspension.

[5.M0NSTER]

Agreed with the others. Sway bars do overwork the tires. Set to softest or revert back to stock. Weight over the tire helps you turn, and killing all the roll is not helpful.

I’ve made that mistake on another car. Outside front doing all the work while the other tire is in the air.

[VR Baron]

Originally Posted by 5.M0NSTER

Agreed with the others. Sway bars do overwork the tires. Set to softest or revert back to stock. Weight over the tire helps you turn, and killing all the roll is not helpful.

I’ve made that mistake on another car. Outside front doing all the work while the other tire is in the air.

Yep. Me to.

[clyde]

At -1.9, you're probably not going to get much more camber without adding camber plates. Maybe a few more tenths, which would help, but not very much. Not sure how much room the non-1LE cars have, but if you put on wider wheels without changing the struts and/or adding camber plates, you may also run into some clearance issues.

Unfortunately, that's just the way the car is. You can't do a whole lot about it without changing/altering some parts and the front tires will not wear evenly. There are a few things you might be able to to mitigate and extend tire life, though.

The first thing is tire pressure. You want it high enough to keep it from rolling over the shoulder too much, but you don't them so high that the tires skate. IME, it's been better to start high and work down because going the other way risks starting too low and getting way too much wear than necessary too quickly. Talk to people running the same tire and size on similar cars. Listen to the ones that are quick and don't appear to overdrive. File what you hear from people that aren't very quick in an "additional thoughts" bucket.

You can flip a lot of tires on the rims so the insides become the outsides (like the RT660s), but some (like the PS4S) are meant to have inside and outside facing sides. And then some tires can be flipped, but they just aren't as good after flipping or may need an event or two before the "turn on" again. When should you flip? Dunno...The worst of the camber challenged cars I've run saw me flipping (or intending to) every other event. From the description you gave, I'd probably plan to flip sometime between 50-70 runs, but that's just a guess.

Also, if you overdrive and barrel into corners going too fast, try getting on the brakes a few feet earlier. Your front tires will wear more evenly and last longer.

Ultimately, even with the perfect pressures and zero overdriving, the outer edges are still going to wear faster. Flipping will help even the wear over time, or, at least, maximize the use you can get out of a pair of tires.

[Christian1LE]

Take it for what it's worth at 2.2 my inner edges wore out faster than the outsides.

[5.M0NSTER]

Originally Posted by Christian1LE

Take it for what it's worth at 2.2 my inner edges wore out faster than the outsides.

Interesting. I have -2.0 and my outsides still wear out but faster than insides with 10k street miles and 5 track days on the tires. Overall I do think this is pretty even wear tho.

[VR Baron]

M12LRV, if you want you can also do the MRC strut mod. With my 19” wheels and 305 Re71s is what gave me -2.6 front camber. With that and running the stock 20” 1le tires for the street I have plenty of clearance . Tire sidewall and roll really affect the wear. With my 1le suspension and only a hotchkiss front bar set soft, my re 71s have even wear across the whole tire, only the outer edge wears more, as expected. But right now at 64 autocross laps the edge is only 1/32” less tread then the inside. Only when the tire has 125 laps does the outer edge get worn down. And only on the front tire, rear is fine.
I know this option won’t help you as re71s aren’t made anymore, but shows what more camber, the stiff front bar and a tire with a stiff sidewall can do for wear. When you get R660s they seem to also have softer sidewalls, my friends running 660s all run 35 psi so not to get rollover. To compare I run only 30 psi on the re71s.
Oh yeah, so far the stock Goodyears for street use also have even wear.

[Christian1LE]

Originally Posted by 5.M0NSTER

Interesting. I have -2.0 and my outsides still wear out but faster than insides with 10k street miles and 5 track days on the tires. Overall I do think this is pretty even wear tho.

The surface overall wears evenly but the inside will cord first.

[5.M0NSTER]

Originally Posted by Christian1LE

The surface overall wears evenly but the inside will cord first.

I'd say time for a new set! Seriously though, they are past the wear bars, I'm not sure how much life can be expected. They are bound to fail somewhere.

[Christian1LE]

Originally Posted by 5.M0NSTER

I'd say time for a new set! Seriously though, they are past the wear bars, I'm not sure how much life can be expected. They are bound to fail somewhere.

Those were my first set of tires, I'm already getting ready to replace them again. My current set probably has 3 trackdays left.