Squishball

New to the forum. I have a 2015 991 Carrera S. Recently had my rear P0’s replaced, fronts still had plenty of tread. Now on spirited driving the PSM activates very aggressively. I can feel the front outside brake engage. I drive the same twisty public road a lot, and the PSM has never engaged prior to the tire replacement. I now find myself turning PSM off, which is probably not ideal. Dealer said they’ve heard of this occurring on 1 other car, which also had only its rear tires replaced. No PSM fault codes. Any clues? Thanks in advance

HenryPcar

Did you just replace one rear tire or both. If its one only, perhaps the PCM senses the different size of these tires between old and new and triggers it.

Squishball

Sorry I forgot to clarify, both rear tires were replaced.

hchandiwala

I recently replaced 2 rear tires (RE 71s) on my ‘08 C2S and had the same issue at the track. I believe I have done this before without issue. This time, the traction control kicked in regularly and was intrusive. Dealership is advising me to replace the two front tires but they have plenty of tread. Going to try this but will save the existing two front tires.

Squishball

My dealer also recommended replacing the front 2 tires, which had plenty of tread left. They also told me it was not realistic to expect owners to replace perfectly fine tires. So, I didn’t. I’m still experiencing intrusive PSM after 1k miles on the rear tires, plus 1 AutoX.

hchandiwala

Any discussion re: need to reprogram the ECU?

Squishball

The dealer did not mention reprogramming the ECU, nor do I know if it is possible. Thanks.

MarkinMD

How new are the tires? Tire Rack says to allow 500 miles to break-in new tires: https://www.tirerack.com/tires/tiret....jsp?techid=5& Or could it just be normal tread squirm due to the deeper tread blocks of new tires?

I once introduced a Datsun 2000 Roadster to a guard rail because I didn't allow enough miles for the tires to get broken-in! Haven't made that mistake again!

Squishball

Thanks for the advice. The original OEM P0 rear tires were replaced with brand new ones. Even after almost 1,100 miles and 3 AutoX, the PSM still kicks in aggressively. However, as you indicated, the tires may simply need more break-in time.

HenryPcar

Something is not right. Unless your tire's circumference is way off spec, I dont see why it will trigger the PSM even after over 1K miles on the tires.

kfmcmahon

+1

Squishball

Nope, stock rims and tires.

Ralph3.

What is the date on the front tires?

Squishball

Date of tires is unknown, but probably original equipment from 2015. So, at worse, they’re 4 - 5 years old