Uneven tire wear

[the_lonely_guy]

I have a 03 base boxster. The tires on the rear wheel seem to have more wear on the outside than on the inside. Is this normal for a spirited driving style. I had and allignment done on this about 8mths ago. The wear is consistent on both rears (more on the outside than on the inside). I read some place that 911s have more inside wear than the outside. I know this is got to do a lot with the allignment and camber stuff. My was was alligned at the dealership as per factory standards. I currently have 17" wheels with michelin pilot sport rib. I did speak with the dealship and they said that it was nothing to worry about. I generally inflate to what porsche recommeds but sometimes go 30 or 32 up front and 34 at the rear

[mee]

Good... it means you drive hard enough :) If you're really concerned, you can get a precision alignment. Basically, the factory allows rear camber from -0.8° to -1.8°. That's quite a range for you to still be in-spec.

[the_lonely_guy]

Really ... I thought I was going easy (compared to the audi I had). Anyways ... So this is really not a problem then is it. I was not really that concerned about the wear, but more with the uneveness of it. I new for sure it was not much or a problem because this uneven wear is consistent with both the rears. The fronts look brand new (i have about 3500 mi on them). So I take it that this is normal.

I really love to take fast turns or corner at moderate to high speeds !!!! :) Thought I'd mention that

Also if there is a negative camber shouldn't the inner side wear faster than the outer? And since this has one heckuva a handling I guess its safe to say that it does not have +ve camber?

Edited May 13, 2005 by the_lonely_guy

[ar38070]

You need to set your alignment to your driving style. If you rears are wearing unevenly then you need to have the alignment adjusted regardless of what the factory setting is.

You do not state how uneven the wear is. If the difference in tread depth (inside versus outside) is 1/16" or less then I would not worry about it. If it is more than an 1/8" then think about having it adjusted.

[the_lonely_guy]

The difference is definitely less than 1/16" compared it using a penny. This approximate. And the surface is smooth so no toe in problems. I spoke with the porsche tech at the dealership and he told me that the rear allignment is 20min. Not very clear what that meant but if I understood it correctly that would be about -0.4 deg camber. And he also told me that since I had the car alligned about 4~5mi ago its definitely not an allignment issue .. He said it just meant I am taking too many turns ;) !!!!!!!! He also suggested that I consistently maintain about 30psi in the front and about 34 at the back. That way the rears dont have to take too much load on the truns

Edited May 17, 2005 by the_lonely_guy

[ar38070]

20 min is .333 degrees (1 degree = 60 min). The factory spec is 1 degree 20 min plus/minus 30 min with a maximum difference left to right of 20 min.

Your tech either quoted the wrong number to you (quoted the maximum difference) or they did the alignment wrong. (I do not know if it is even possible to adjust the suspension to only have 20 min of camber.)

In either case you should verify. You should be able to get a written statement as to what numbers the car was aligned to.

[the_lonely_guy]

I think he did not know it meant himself. All he told me was the service guy who worked on the car said that it was 20min (At first he didn't even know that this car had a staggered wheel set up). I would have to verify it anyways and will be getting it realligned. The only guy who knows what's going on is the actual service guy who works on the car and to make matters worse there is just one guy there who works on porsches !!!

I was confused because having the outer edge wear slightly more than the inner edge with -ve camber didn't seem right. When I was talking to a 911 owner at the dealership, he told me that genereally if the car were cornered heavily the outer edge would more than the inner depending on the amount of -ve camber. And looking at my car he said that there was very small -ve camber.

I wanted to confirm this behaviour and know what those guys were going to do with the allignment. I never track this car and am not very familiar with these things