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After the first day at Laurenburg I noticed that my front tires no longer had tread on the first inch of the outside edge. I have been running them with 32 psi in the front and 36 psi in the rear. I was not getting excessive rollover at that pressure (the wear is just down to the top of the little triangles on the side of the tire). I am going to have the tires flipped since I can't rotate them to the rear.

The tires are only used for autocross and getting to and from the event.
Will I notice any difference when I autocross? Will they be really unstable driving to and from the event in heavy rain?

I am going to increase the front pressure to 38 psi. Should I go higher?
With 32 psi a pyrometer showed 145 outside, 135 middle and 125 inside.

Is there anything else I can do to decrease the edge wear and stay stock. The Boxster only gets about .5 negative camber.

I had the toe set at - 1/8 total toe in the front just before the event. Stock toe is + 1/16 total toe. Could this have caused more wear?

The tread on the rest of the tire is 5/32. Would I actually get more life out of the tire if I had them shaved to 2/32 like Tom does or is that for performance only? I don't think I would want to drive them to an event with that little tread.

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Mitch Moore

I would just run them until they're about half-tread in the middle of the tire & then flip them. That's what I've been doing & haven't had any problems. There's a lot of rubber left there after you lose the tread, so you should be okay for a while.

The 1/8" toe-out should cause excessive wear on the inner edge of the tire, not the outside.

Never shave an Azenis - all you'll do is shorten the amount of time it takes for you to need new tires.

I haven't seen any difference in performance after flipping them, but I don't drive on them on the street after they've passed the half-tread point unless it's 0% chance of rain.

You might be able to decrease edge wear and add front grip with a bigger front sway bar - works for Subarus. Or you may not even have a front sway bar -- I have no idea.

Another way of decreasing front tire wear would be to pitch the car into corners, get the back tires drifting/spinning & countersteer. This would increase the rear tire wear, though. But it would be fun!

I think the tire temps tell the story, you need more neg camber in the front. And more tire pressure probably won't help much. Like kevin said with toe out you should have more wear on the inside not the outside, but 1/8 really isn't excessive either.

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91 Jetta GLI STS/DSP 111
85 Porsche 944 ASP 11
http://www.blackforestindustries.com

On the Suabru's you can also get a little bit more camber by taking all the "slop" out when you get it aligned. Loosen the top mounts with the suspension unweighted and push them towards the center of the car, and pull the bottoms away, then re-tighten. I don't know if this will work on your car. Stiffer struts/shocks + sway bar to help keep anything you get.

These are what mine look like after last year and this year:

http://www.theb.org/~bill/old_busted.jpg


Without too much of a hi-jack, can anyone tell me if these are worth flipping, or should I just call 'em cooked and get new ones?

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-Bill Martin
02 WRX DS#44

Mitch,

Tom and I haven't shaved our Azenis all year. And I think Kevin is right about shaving them just shortening the life of the tire. Honestly, shaved tires may be .1 or .2 faster when new but they will be worn out much sooner.

It sounds like the main culprit of your tire wear is negative camber or lack there of. The tire temps confirm that the outside 1/3 of your tire is doing most of the work in the corners. Going up in pressure may help a little but it won't really solve the problem. You can easily go up to the mid 40's. I'd suggest bumping up the pressure and then take some temps to see if it helps or hurts the distribution across the tire.

We've had success with flipping Azenis on the rim to use the other edge as well. So you can definitely get away with doing that to extend tire life without hurting your performance.

It might be worth asking GH Sharp if there is anything you can do to help the front camber. He had (has??) one or more Boxster's so if there is anything you can do to legally gain negative camber he would probably know what it is.


Shawn

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OK so I'm back in. Now which tire should I buy??

Thanks for all the great info. Looks like all I need to do is flip the tires and by the time the edge wears down again the rest of the tread will probably be down to the wear bars. Wish I had gotten the car with the sport suspension package. I believe it had a stiffer swaybar. Maybe I can pick it up on Ebay.

GH Sharp told me last year about getting negative camber by moving the struts in. He said that I would be doing good if I got .5 negative.

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Mitch Moore

Mitch,

Why do you want toe-in on the front of your car? I would think you would like the turn in better with the factory setup of toe-out just a bit. Like the +1/16 or +1/8 total. Are you trying to deliberately induce understeer?

Not sure on a Boxster but on the Vette toe-in in the front sucks. Toe-in on the rear however is a good thing. Due to the split axle. I'm at -1/8 total toe-in.

On the front camber I feel your pain. I can get -.8 on the drivers side. More on the passenger side but I kept even based on the worst setting. It can be easily fixed to get it closer to -2 but unfortunately it is not an AS mod... Now on the rear I can get all the negative camber I want.

With those settings my R-comps are showing pretty even wear across the whole tire. But they don't require heavy negative camber like the Hoosiers do. My street tires are showing no ill wear in daily driving with this setup. And it's lots of fun at the on/off ramps

Graham

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http://www.greywinds.com

negative toe = toe out