dirtrack49

Well it's that time again for another set of rear tires. My last set made it to 5,300 miles before hitting the wear limit on the right rear tire.

I am running Pirelli assemetrico N4 Rosso's on all four. Wear appears even on all four with the exception of the right rear that makes it to the wear limit I am guessing about 1000 miles earlier than the left rear. The inside wears slightly more than the outside. All mileage is on twisting roads. Maybe no more than 300 miles on freeways. I do drive rather hard, however, I do not accelerate hard from a dead stop.

Today I ordered another set, but had the tire people rotate the tires and wheels on the rear. (LT Alloy 5 spoke).

My questions are, is this tire expected to only last a very short time? Is there something wrong with the right rear wearing out first? Should I rotate the tires about every 3000 miles to even out the wear?

Thanks for any and all help.

Tom L
2002 C2

Dr_KarlB

Tom,
I got the same mileage from a set of Pirelli rears as you. I do drive quite hard too.
Earlier this year i got the alignment adjusted for more front camber, and they found the rear toe way WAY too much. The wear was even, but the tires would scrub sideways when driving in a straight line, thus wearing them out reall fast.
I wasnt expecting much more than 8,000 miles on the rears though.
My tire guy wouldnt rotate the tires... said it would cause bad issues with the handling and they would have to unmount all tires as they have a specific rotation direction.

porsche-t

That's strange, I have about 18,500 on my Pirelli's with no tire rotation and there is still some tread before the wear marks. They are starting to get some road noise now.

dirtrack49

Dr KarlB,

Interesting note about the possible cause of your same tire wear. I will see if I can find an alignment shop that can do my Porsche here in the High Desert.

After they rotated my rear wheels without taking down the tires, I really don't find any difference in the handling, although I am driving a little more conservative until I put the new tires on next week.

The tires are assemetrico and have an outer and inner mount position. By swapping the rears, the tires are still positioned correctly on the rims without breaking them down. My wheels are light alloy 5 spoke 18" so they have no direction to them. The only thing I was concerned about, was the possibility of the radial tire having a problem now that they are running in oposite directions from how they were originally put on.

I only drive this car on canyon roads and assume that powering out of turns takes it toll on the rears. Although I drive an old MGB rather hard on the same roads, I can probably get six times the mileage out of a set of tires. Of course, we are talking about two different types of animals.

I guess this must be the price we pay, to have way to much fun?

Tom L

K996

I have a little over 10k miles on my most recent set of Michelin PS2's. My last pair only lasted about 4k, the difference is that I had the toe-in altered to be less agressive.

This has made a HUGE improvement in tire wear at the cost of slightly less planted handling.

I didn't bother with rear wheel left-to-right rotation as I personally don't think it would make that much difference if the tires are properly (ie, evenly) aligned.

dirtrack49

K996,

That certainly makes sense altering the toe-in, however, how much handling performance is given up to help save the tires?

Anyone have or know where I can find the specs for rear toe-in?

Thanks,
Tom L
2002 C2

Tonger

Dirt,

The way it was explained to me is that the 996 really doesn't have a limited slip diff. Therefore the right rear is the "drive wheel" and tends to wear out first. This has been my experience as well. I'd really like to see 8-10K out of the rears though. I'm also running the Rosso's and I swear the tread just evaporates on these things. I'll be switching to the PS sport ribs as soon as the fronts wear out to get some better wear characteristics.

Hope this helps...

Dr_KarlB

I got mine done at Custom Alignment (all the indy and track guys go to them)
I got Aggressive Street ALignment
This is what the print out said:

Front Camber: -.8 to +.3-degrees set to -.7
Front Toe: 0 to 3/32" set to 1/32"
Front Total Toe: 0 to 5/32" set to 2/32"

Rear Camber: -1.5 to -.8 degrees set to 1.0 degrees
Rear Toe: 0 to 3/32" set to 3/32"
Rear Total Toe: 0 to 6/32" set to 6/32"

Before Alignment the total rear toe was 13/32" !!!!!! Over twice the spec, thus the rear tires travelled over twice as far sideways as they should... thus half life :-)

BTW this is for a 2001 C4 Cab

JVictor

Front tires: Inside wearing somewhat-not radically- faster than outside edges. Time to replace. Is this typical with factory spec alignment on 2000 C2? Pilot sports with about 20K (good wear, huh?) jVm