multi21

I can't figure out why I'm getting excessive wear on the inside shoulders of my rear tires. I used to run less than 2mm toe in, currently running 4mm toe in and -2.0 neg camera in the rear (996 GT3).

The guy that aligns my car wanted to bump the rear neg. camber up to -2.3, but I told him not to as I was already getting excessive wear with only -2.0.

Doesn't matter if it's a street tire, medium grade r comps or Hoohoos.

Any thoughts????

LVDell

A couple things. It might be side dependent depending on the track you are running. Also, if you are running 315's in the rear you need very little camber in the GT3. Ask me how I know Once we dropped the camber back a bit the inside cording problem disappeared. I ran 2 mm toe in on each side in the rear as well.

multi21

Good points. I don't have a "home track" and travel to various tracks in CA, NV and sometimes AZ so there isn't the issue of running a particular way every time out. I also AX the car.

As far are tires sizes, I have tried 285, 295, 305 and 315s all with the same issue. For those tires that can be flipped, I do so to even out the wear.

LVDell

So is it both tires or just mostly one side?

FYI...I never had any problems with uneven wear at Spring Mountain since there is a good mix of both high lateral G load left and right turns. However, at a track like VIR with really heavy left turn loading corners, I saw much more tire wear (cording) on my left rear tire.

RedlineMan

Could be excessive use...

Seriously... PYROMETER. It's a much cheaper and more effective way to refine your aligment specs than wearing out tires!

Veloce Raptor

Plus Juan.







Professional Racing and Driving Coach

Bob Rouleau

Dell - what camber did you run on the GT3 rear? I started at 2.4 and wore the insides too fast. Dropped it to 2.2 but too early to tell if that's the right setting for 12 inch wheels with 315's.

multi21

both sides...

Spring Mountain -- Full course CW.

Las Vegas outside road course -- CW.

Fontana/CalSpeedway Roval -- CCW.

Fontana/Calspeeway infield-- CW.

Buttonwillow -- both CW and CCW

Phoenix International -- CCW.

Laguna Seca -- CCW.

Willow Springs -- CW.

Streets of Willow -- CW and CCW

Pretty even split each way

multi21

LOL!!! Someone in my household would certainly agree with that statement....

KurtC

I would think your increase in toe-in is what's wearing them more quickly. Toe will have a bigger effect on wear than the camber, in my experience.

Veloce Raptor

Wouldn't toe IN cause the outsides to wear first?







Professional Racing and Driving Coach

A.Wayne

Dats a lot of Camera for rear tires

KurtC

That would depend on the camber. With no camber, it'd just wear the tire evenly, more quickly, with positive camber, the outside, negative, the inside. The toe-in forces the left wheel to turn in a little to the right and the right one a little to the left so both are a little off from straight ahead. When rolling along, the tire is scrubbing against the road rather than just rolling over it. You want a little toe-in in the rear for feel and handling but too much will wear the tires quickly.

SundayDriver

Not necessarily. Think about extremes and I find it always helps me understand what may be happening. Take a tire with 15-20 degrees of neg camber. Down all the straights, you are running only on the inside edge. Now add too much toe and you are also scrubbing the tire sideways (adding to the wear).

Now come back to reality of 2+ degrees neg camber. The tire is still taking most of the load on the inside edge down the straights. So toe is adding the sideways scrub to that and accelerating the wear.

Rassel

This could be both setup and how you drive the car.

Same problem with all types of tires, makes me think it is perhaps drive technique. (If your setup is not completly scr*wed?).

A good instructor should both be able to feel if something is wrong with your setup and also see if your driving input needs to be altered. I'm sure there are more than one here on RL who can help you.

For fine tuning and sorting things out yourself. A pyrometer and one of those small handy data acquisition boxes are powerful tools. If you're not used to problematic approaches with Data, get a helping hand here too. It's easy to pull wrong conclusions or mask errors with wrong "counter measures".

Hope it works out.