Rear tire wear?

My rear tires are down to the wear bars after about 6,000 miles. This cant be normal, can it?

Did you install those tires brand new 6.000 miles ago??? they should last at least 10.000 miles depending on brand and driving conditions..

mine last about 6k or so too.

dealer installed them brand new when i bought the car 6K miles ago. cant remember the brand - it was either michelin sport PS2 or conti sport contact. but its definitely a soft sport rubber.

You've been using them haven't you!

Not unheard of depending on tire, alignment, driving style, etc. Definitely on the low mileage side but within the normal range reported on Rennlist. Was the wear uniform across the tire and both sides?

If your allignment specs (specifically rear camber) are within, but on the more negative setting of the range, your rear tires will wear on the inside half of the tires more than the outside. This is normal and is dictated by the car riding on only the inside half of the tires when driving straight. to reduce this type of wear, set the camber to the minimum of specs.

aha.. as long as i am not an exception to the rule

Sounds like you drive like me. Rear tires dont last long with my alignment and driving style.

yeah i know what camber is i am pretty sure mine is within specs, but i'll check out when i get new tires. i wonder if i can rotate existing rear tires or are they unidirectional?

unidirectional on all the ones I've seen - so you're SOL. Was the wear even across the width?

Pics of the tires? I am sure we could tell you exactly what the problem is.

I wasn't the greatest at math, but I think the ratio is something like: Right Foot Angle / Rear Tire Wear

I think you missed my point. If the camber is WITHIN specs, they WILL wear in this fashion. The only way you can reduce the wear and also maintain good handling, is to reduce the negative camber to the minimum allowed.

My first set of rears lasted about 6K miles, but there are 2 factors that effected this. My fronts only went down 2/32's in the same amount of distance. I ran the Porsche recommended 44 psi in the rear and they wore out in the center with almost half the tread remaining on the outside. This is far too much tire pressure for wear and contact patch. I now run 38-40 psi. The other is I did several track days on those tires, which certainly shortened their lifecycle. Not a problems since I now have race wheels and tires. i run a lot more camber than factory specs (-1.6 front and -1.9 rear), but i am not having wear problems due to camber (inner or outer edge wearing faster).

I run minimum camber, per specs, 44 psi and now get probably 13,000+ safe miles out of my rear tires (non track). Prior to reducing camber I would get 8,000 - 10,000 miles. Treadwear is more even now, but remains more on the inside half, which is what I expected. Front tires run at 36 psi and I get 25,000 - 30,000 miles out of them.

I got about 5000 out of a rear set of Pirelli's. I had the alignment checked and re-set and the rear toe was almost double the specs. The rears were scrubbing sideways twice as much as they should.... great even tire wear though :-) With the new alignment and Bridgestone RE050 PP's i have 3k mileson them and loads of tread left... work good at the track too !

I'm running Pirelli's on mine and I'm up to 20K+ on the new set with even tread wear across the rear tires. (40psi)

If you have 20,000 on the rears and the tires are still within legal limits on tread, then your allignment is nowhere near within specs or never drive more than 40 mph. No problem running less camber than spec'd, but not as good at handing.

Porsche-t 20k???? on one set ! Do you use the pedal on the right much ? My car has only 18,000 miles and im on the fourth set of rears !!!

is somebody embelishing a bit?

I have driven my car to California twice, one way from California and I do jaunts down 1604 at 120mph regularly. No Dell, I'm not embellishing. Car had 10K on it when I bought it and it is slighty over 30K now. I need tires now and it handles very well, and I do drive it using the pedal on the right.

Where in God's name are you hitting 120+ on 1604? Good for you though That might very well be a record here with 20K on a set of rears.

Between Judson and Redland Rd. Yeah, I couldn't believe it either. they are making road noise, but they look like they can make one more one way trip to Cali. BTW - I did get caught doing 80 in a 70 on 1604.

Ah, now I know how you hit those speeds! I used to live out in Sonterra and remember the good ole days BEFORE the traffic. But from 10 all the way to 35, traffic now blows on the loop.

I'm another one, in the dealer last month (20k service) I was advised that I need my first set of new rear tires in about a month...and yes...I drive it everywhere. I have no idea about my alignment, all seems to be fine.

Also Highway 90 going to Lackland (130+). I don't do jackrabbit starts so I guess that helps. And 1999Porsche, the dealer in California did the last alignment, so I guess they did it right ( and filled it with 0W40 Mobil 1 after it was done!)

porsche-t, it sounds that you are on the original tires from '99 (check the manufacturing year on the tires). If you bought the car with 10k miles, then the previous owner might not have replaced the the tires at all. I had the same experience with 2 low millage older cars. After some years the rubber gets extremely hard. Have you ever driven your car on wet roads and wondered why you have no grip? I once owned a BMW Z3 2.8 and it had the original tires on it, a 5 year old car! On wet roads I was able to spin the car in almost every gear by just slighly pushing the trottle in turns. When I replaced the tires, the traction of the car changed completely.

No, not original tires. The car came with 18" Sport Designs and they were changed to Techarts and Pirellis just before I bought it.

I am getting ready to replace my PS Ribs. Fronts have over 23k on them, rears over 16k, with the rears wearing most in the middle of the tire even though I ran 40psi for the most part in the rears. Gonna go with a full set of N1 Pilot Sport Ribs.

I don't care how many allignments you have had and how many people have said it is within spec......it is NOT within specs or you are running plastic tires. Highway driving at speed rips the inside half of those tires faster than any other type of driving. You car may handle fine for your driving style, but your camber is less negative than specs require. Many driviers run this setup, but they are not aggressive corner drivers and it works out fine. A posting of a picture of your car'ss stance from behind, showing the tires would be interesting to look at. If your Pirelli's really have 20,000 miles on them AND your allignment is within specs, it should be quite noticable at night as you will see sparks behind the car.

1999Porsche, get over yourself! All I am saying is my car does have a little over 20K on the tires AND I do need new ones now. As far as my driving style, no I don't take every corner like it's the last time I'll ever drive, but I have driven it hard (if you ever lived in Southern California and traveled Angeles Crest Highway you would know).As far as sparks coming out of the rear, yes the tires are worn on the inside. LIKE I SAID, I DO NEED NEW TIRES NOW. BTW, pay the $17 and become a member.

I'm up for new ones as well. I got 12,000 plus on them but they are pretty well used up. All driving was on the street, no autocross or track time. Oh well, $600.00 dollars later and I'll be ready for Spring.....

I've put about 14k on my Goodyear F1 GS-D3 and they are looking like they are ready for at least another 5-10K. I don't know how much more mileage for sure, but they look surprisingly good - and I don't think 20k is out of the question. Yes, I drive quite fast and have gone on a couple loooong road trips, plus I am an entrance/exit ramp warrior.. so I actually do use my tires and power. All German Auto did the alignment on my car the day after I bought the tires, and my tread wear looks pretty even. Someone mentioned that if your tires last 20k, that your car's handling probably sucks or other such nonesense.. sorry but I disagree there! That is quite the all-encompassing blanket statement there.

But seriously JKB, the 996 rears have the toe inn and neg camber dialed in them. The camber gets worse if you lowered the car from stock. No way around it. But if they(tires) are really wearing out fast without you driving aggresively, I would have the allighment checked.

Negative camber is most wearing to the rear tires when NOT driven hard. i.e. jackrabbit starts, aggresive cornering. The camber is set with the car sitting at normal suspension height. Any reduction in the rear height, such as rapid acceleration or heavy luggage or passenger in the rear seats, REDUCES the amount of camber and the tires flatten out, decreasing the uneven wear. The effect of cornering is even more obvious. The straighter and steadier you drive your car, the more your riding on the inside half of your tires. This is why a car with negative camber that are driven primarily on highways or straight roads, will always, not sometimes, but always wear out the inside half of the rear tires before the outside half. This is a rules of physics and not an opinion. The greater the negative camber, the greater the wear difference. So, to claim that aggressive driving will lessen this type of tire wear is incorrect.

I had my negative camber adjusted after suffering premature inner shoulder wear on the rears. In fact, the shoulder went all the way through on one side before wifey even knew anything was wrong. She was driving home from work, and went an additional 15 miles home without realizing! The tire stayed on the rim, the rim was undamaged, but it got red hot, and I could put my hand through the hole in the shoulder on the inside! CHECK YOUR REAR EVERY WEEK!

Just saw mine today both rears corded worse then that! <5k mi. I also have -2.4 deg camber. damn toe is probably off again.