TheDatanator

Folks I have searched prior to this post but found nothing.

I'm ready to replace my P-Zeros in my '14 981 CS. The fronts are looking like they have at least another 12K left in them. Maybe 10.

I really want to convert the car to Michelin PSS but don't want to buy a set of rear P-Zeros unless I have to.

Is it feasible to go ahead and put the PSSs on the rear while having the P-Zeros still on the front? Or am I asking for issues? I do not track the car but do enjoy aggressive club drives 2-3 times a year.

Thanks in advance for useful guidance...

Cman21

Its best to have the same tires on the car. The PSM & ABS systems can get a little crazy when you push the car near the limits. I was in the same situation last year needing rear tires with a lot of life left on the front tires. It was only a 300.00 difference to go with four new MPSS tires vs two new P Zeros

Cman21

Macster

If the fronts are that close -- 10K to 12K miles -- of needing replacement I'd be tempted to just replace them now.

I have run the fronts for around 40K miles. While they have some tread left at this stage -- easily another 12K miles -- they are hard and noisy and do not grip as good as they did.

(The last set of front tires I left them on when I replaced the 2nd set of rear tires. The fronts then had around 40K miles on them. I drove the car but as the front tire wore the car's handling got pretty squirrelly. I didn't push the car to the point the rear tires needed replacement again but instead just had the fronts replaced. The car's transformation was quite striking. All the squirrelliness went away along with a whole heck of a lot of tire noise.)

There are some owners who mix and match tires and brands and report no issues. There are some who do this and report issues.

I have gone through a number of sets of tires over the years -- at 290K miles on my Boxster and 132K miles on my Turbo I have gone through some tires -- and have never mixed brands not even N numbers.

My reasoning is when I test drove the car I was perfectly satisfied with the way the car felt, the way the tires behaved. Further as I drove the car and lived with the car in all kinds of driving not once could I find fault with the tires. (Admittedly there were a few times I wish I had real snow tires on the car but that was my fault for trying to use the wrong tires at the wrong time, not the fault of the tires.) Thus I have no reason to temp fate and play with tire combinations. If all goes well, well, that's one thing. But if not then I have to eat the cost and have the tires sorted and I do not want to have to spend the extra money nor take the time to have this corrected.

PNWR968

Always use the same tire on both front and back. Our PCA region won't allow autocross, DE, or car control clinic entry if the tires are not the same.

Sven76

No way you ever mix tires. And certainly not on a high performance car. Can get you all kind of unexpected and unintended reactions, oversteer, underseer, PSM reaction funny,... Tires are the only thing which connect your car to the road, so you want to make sure you have the best possible option.

In you position, I'd get another set of P Zeros for the rear and then swap next time to Michelin. Rear tires for me rarely last any longer than 6-8,000 miles, was going to 2-3 rears before I had to replace fronts on other mid engined cars.

thomapa1

Don't mix tires. I did it at a DE - tons of PSM and ABS activation until it threw a code. Not optimal. For a small amount of money, keep them the same...tires and brakes - pretty frikking important.

TheDatanator

Thanks everyone for the sage advice.

meteor10

Yeah I just went through this same situation, rear P-0's shot and fronts only half shot. I ended up buying 4 new MPSS instead of just 2 new rear P-0's. Fresh tires all around for the new season.

TheDatanator

are you happy with your choice or would you have done another set of P-0s so get more out of the fronts?

Bill Lehman

Do a couple of DEs and kill your fronts. Don't mix tires.

zadar

Electronics don't know what brand tire is on your wheels.
If you don't have problems with worn out rears why would you have with new ones

meteor10

I think it was the best decision for me as I wanted to try the MPSS on the 981. If these rears wear out much faster than the fronts I would consider 2 new rear MPSS at that time.

mikefocke

In Germany where they drive much faster than in the US the requirement was 2 of the same on an axle. Even same tread depth.

My first water cooled Porsche came with same brand, different tread design Pirellis. They were fine. Designed to work together. Porsche approved N types.

If the ABS is calibrated to work with 4 times as much tread depth on one axle as another...

Not knowing where you live or what conditions you drive on....

Having said all that, go look at the tirerack tests of tread depths in the wet and you'll not hesitate to pay a little more to have full tread depth all around.

I'll cheat and just give you the results. the difference between a new tire and one worn down to 2/32 (legal limit in many states) in a test on a water soaked surface was an almost doubling of stopping distance! 4/32 deep tires took about 50% longer to stop than new tires.

New - 195 feet

4/32 - 290 feet

2/32 - 378 feet

Even more startling to me is that on a 2/32 tire, in stopping tests in the wet from 70MPH the new tire would have stopped the car where the worn tire would only have slowed the car to 55MPH!!!! 4/32 would only have slowed the car to 45!!!! Bang.

PhilNotHill

Thank you for posting.

I always replace all four tires when fronts or rears are too worn. Your tires are your life. That's your only contact with the road...not a good place to try and save money IMVHO.

doborder

That is great info... Should be a sticky or something
Everyone should know this! Learn something from the forum everyday!