Tire wear question - 986 Forum - The Community for Porsche Boxster & Cayman Owners

So the passenger side rear tire has worn in the middle 8" of the tread on two sets of tires. The fronts are fine and the drivers rear is fine but this is twice now that I am having to replace the rears because that tire wears out. I could understand it if I was a drift person or a big burnout fan but I do not ever intentionally spin the tires. The diff is open, I wonder whether this is an alignment issue or if a LSD would solve the problem. It is a 3.6L and I do like to accelerate hard once I am out of first gear but I assumed that the PSM would minimize any wheel spin and I cannot hear it or feel it spinning. It feels completely hooked up. Thoughts?

Air pressure, alignment or wheel spin. Over inflated tires tend to wear in the center. Under inflation tends to wear both outer edges evenly. Poor alignment tends to wear inner OR outer edge. What are your expectations? My car rarely sees straight line highways and spends a lot of time in the canyons. 5000 miles on a set of PS2 rears is typical for me.

Cheapest/easiest way is to check alignment and tire pressure. PSM won't kick it until very late, it won't save you from tire wear.

When I spin the tires the right rear center tread wears the most. Minimize this by reducing to 33 psi. , rotate rear tires side to side, no need to replace tires in pairs. PS: PSM first available in 2001

Alignment and/or air pressure. Normally, the standard rear alignment will wear the inner 2/3's of the tire. The outer 1/3 barely sees any wear until you push the car hard in the corners and the camber changes to straighten up the tire so the outer 1/3 sees action. If the alignment is off, then the car could be running mostly on the center 1/3 of the rear tire rather than on the inner 1/3 + center 1/3. This would tend to double the wear on the center 1/3. If the air pressure is high, then the rears will wear more towards the middle as the air pressue will reduce pressure on the inner 1/3 of the tire and have the same effect as poor alignment. Have a good alignment done and consider reducing the rear air pressure a few pounds. Also, check the passenger rear for anything bent or worn like a wheel hub or suspension component.

It may be the open diff instead of, or in addition to the alignment. If the transmission favors one side, you may be getting more wheelspin on one tire than the other. Could be due to some slight difference in suspension geometry or cv joint geometry on one side. In which case, LSD would help even tire wear. But I'd suspect the alignment of the rear suspension first.

the wheel itself could be bent.

Thanks for all the input... We do have a good tire shop here with a four wheel alignment machine and I trust the guy because he lets me help. His staff puts up with all of my particular requests, hand torquing lugs with torque wrench and stuff like that. I guess we can do the alignment when I get the new tires for the rear, I was looking today and the right is more worn than the left but the left aint looking too swift either. The rears are Yokohama S Drives and they lasted me about one season (6k miles I would guess) the Michelins on the front look just like they did when the yokos went on the back. I think I may have to drop the extra coin and go with the Michelins on the rear as well. Call it payback for all the excellent racing they sponsor around the world (and the stats for the pilots are superb). If the alignment is spot on then an LSD might be in order.

6000 mile tire life would upset me and it sounds excessive, even for these cars.

Reminds me of the old Pirellis!

"Old Pirellis"! My Russos are wearing so fast you can use the rubber to repave the road. They are wearing about 1/10 per thousand miles on the front and 2/10 on the back.

and of course that would have zero affect on tire wear

I got just over 27k miles out of the rears (falken azenis ST 115's) and they still have some tread left but the inner 1" edge of the tire is really worn. I am getting HTZR II's to replace them and get another alignment. I would be mad if I could only get 5-6k miles out of a pair of tires...maybe I am not driving it hard enough

I bought directional tires,not to happy with the choice.

Just looked at my tires. Fronts seem fine but the rears seem to be wearing on the outer portion of the tire. The inner part of the rear has a lot of meat left whereas the outer seems to have significantly less tread left. Any thoughts on rear tires wearing like that? Just checked the pressure after coming back from a ride so the tires/car is still warm. fronts 235/40 18 reads 35.5 in both rears 265/40 18 reads 36.5 in both

HTZ R II or III ? i have the III and won't be buying them again.

You should have more wear on the inner part since it's negative camber all around. You should also check tire pressure before you drive, not after.

You should have even wear on all tires unless you tell your alignment shop you would like to sacrifice treadwear for increased cornering capability. Tire PSI increases 2lbs. during normal driving so keeping this in mind it is ok to check psi anytime just be sure before reducing psi on a hot tire.

The car rides so much smoother now. You just don't realize how far gone the old tires are until you have new rubber.