996Pilot

After drifting a bit through a corner on this mornings spirited drive, I pulled the rears off to examine the tread. They're done! Exactly 7300 miles and we've got a few wear bars even with the tread. I did however notice that there is slightly more wear at the center than the outsides. I'm running 42psi on the rears (36 in the front) so it's looking like we'll go down to 38-40 for the next set of rears (that WILL NOT be Conti's). Since I do not track the car I'm probably going with Sumi's for the next set HTR Z-III's. Current size is 285/30-18 on the 2002 C2 Cab. on the factory ultralight 5 spokes. Does anyone know (for sure or from direct experience) what maximum width I can run on the rears?

jeneric996

You're either having too much fun in the corners or your alignment (toe) is slightly off.

You could go 295/30 - 18 and you will be within factory specs of 25" rolling circumference. In fact, the 295 is closer to the 25" than the 285/30 - 18. However, this will induce slightly more understeer because of the wider rear without changing the size in the fronts.

tooloud10

Almost seems like there'd have to be something wrong for someone to run lower than recommended pressure in the rear and still get more wear in the center than on the inside of the tire. 7300 miles to the wear bears doesn't sound absolutely ridiculous to me, though, depending on how the car was driven.

Byprodriver

The first difference you will notice with the 295/30 size is slower acceleration due to reduced gear multiplication followed by difficulty finding proper air pressure for even treadwear since you are putting a wider tire on a wheel Porsche intended for a 285. I bought a Carrea II wheel & tire pkg. from a Porsche dealer & was disappointed to see they were only available with the Conti sport 2's since Conti's usually have a harder tread compound (increases treadwear) than I want. I was pleasantly surprised with the performance of the Conti's yet still impatient for them to finally wearout so I could replace them with PS2

Chart505

I get about 7,500 or so on my rears as well. My car is lowered as well, which I think may promote quicker wear. I have the HTRZ IIIs on my BMW and I like them alot. I have T1Rs on the Porsche now.

Gaspasser19

It's your alignment. I got 19K miles out of my last set of rears. The fronts went almost 30K.

Macster

My 03 Turbo came with Contis and rear tire life has been pretty good at around 15K miles save once when a dealer gave the car a crappy alignment and then rear tire life dropped to under 8K miles. Fronts easily go 2 times that number of miles.

This last set of rear tires wore down to the bars and the right rear picked up a nail and a piece of metal. I had to replace the tires and since the fronts had way over 30K miles on them had a Sacramento dealer put on a set of Bridgestones. So far with way over 5K miles on these tires tire life looks to be about the same as the Contis. And that is a good thing.

Oh, I run factory tire pressures front and rear and I see no excessive center tread wear patterns. My info is a bit of this is normal.

The alignment must be spot on. I learned long ago with my Boxster (and had the lessen reinforced once already in the Turbo) proper alignment critical for maximizing tire life.

However, if with the best alignment in the universe a heavy throttle foot can eat tires up very quick.

Sincerely,

Macster.

Dennis C

I"ve got about 15K on my Sumis, and they still look pretty good. The wear is quite even, and I run recommended pressures. I got a four wheel alignment when I bought the tires.

redridge

it all depends on how you drive... if you drive aggressively and some DE, The 5k-7k miles is about right, yes alignment is a huge factor.

rpm's S2

Driving aggressively but no DEs I have nearly 10k on my Contis and it looks like they will go to 15. Sounds like alignment.

ivangene

in case you want to read some stuff

https://rennlist.com/996_faq/b.htm

996Pilot

Four wheel alignment was performed by a reputable shop the week following installation of the Conti's. I don't see too much wear due to camber but I'm not sure if there would be any signs on the tire indicating improper toe-in settings. For sure we'll get another alignment when the Sumi's go on. My '99 C2 Cab used to average about 10K miles on the Pirelli P Zeros. I thought that was low - but this??

Pac996

Center wear is too much air pressure which makes the center bulge to take the main contact suface duty. Possibly a combination of rim width pinching the tire highlighting center contact results. Higher pressures have the tire stiffer which makes them take longer to heat up. A soft pressure gets tires warmed up the fastest.

IrocMan

less than 10K even if you drive crazy sounds pretty odd.
I got 14K on my previous PZero Nero tires (factory 295-18 setup). I have noticed that my alignment tends to go wrong every 4-5K so you could have the same issue, I take advantage of the warranty WheelWorks offer to re-align for free.
I'm currently riding with Bridgestone Potenza Pole Position tires, with same factory setup - it's been 3K and they seems to be still at 100%!

BTW you should have kept the Piper. That's a good bird

flyingpenguin

+1 on the alignment. Not sure about the Sumitomo HTR-Z-II's. They are directional and also have an inside-outside, which makes them unsuitable to flip on the rim after 4-5K, almost doubling the life of your tires.

Joost