Inbyten

I've got a '14 C4S. I replaced the P zeroes with the MPS4S recently. I put about 200 street miles on them and then took the car to the track for DE. After 1.5 days and 8 sessions, the outside of the front right tire was corded and missing chunks of rubber (track was run counter clockwise). The front left tire was missing a few chunks on the outside, but wasn't nearly as bad. I was running hot pressures of 33/39. The pressures seemed fine on my earlier sessions, and I didn't see evidence of the tire rolling over much. Has anyone else seen this? This seems abnormal to me. Any thoughts? Thanks!

LexVan

Normal.

What were your cold pressures? Probably 30 or below.

You ran a street tire on the track, and probably had pretty low cold pressures. Hit any curbing at apex?

Price to pay for the DE experience. Consumables. Order two new tires from the Rack.

911-TOUR

As LexVan stated. Normal.

LexVan

And technically, it sounds more like chunking than cording.

Assuming your have a pretty normal and neutral alignment?

Maybe even the 4S exacerbates this wear?

Inbyten

Yep, I hit a bit of curbing. Alignment was a normal street alignment.
I did 5 DE days last season on the p zeroes without this issue. I just assumed I'd at least get through the weekend on these tires.
I assume a dedicated track tire wouldn't have this issue? Thanks for the feedback!

Inbyten

Forgot to mention-- my cold pressures in the front were in the mid to high 20s. But I'd give them a lap to warm up before starting to drive hard.

erko1905

That's quite surprising. I ran my MPS4S last season on my 14 C4S through 15 track days, 4 sessions per day. With camber in the front maxed out, I did get slightly uneven wear (ie outsides wearing tad bit faster) but never had chunking, cording issues. I ran 35psi hot pressures all around. Reasonably consistent grip throughout the season.

I'd say it's either a suspect alignment or a bad batch on that tire. Since your track was running ccw and the right outside wear I'd guess too little camber. What are your alignment specs?

These tires don't mind starting high 20s cold into the session and getting warmed up through a lap or two, with some straight line hard breaking and accelerating.

worf928

tstafford

Agree with the above two posts - street alignment will eat up tires on the track. But it stills seems a bit severe to me.

Inbyten

I had the alignment done by my dealer 2 days prior to the event when the new tires went on. Fronts were -1* camber, rears -1.35*. Everything was in 'normal' spec for a street alignment. The steering wheel was a few degrees off center when I got it back, but I assumed that was just cosmetic. I have to take it in to get that fixed.

erko1905

-1 front -1.35 rear is pretty light on camber. Off center steering wheel is also an issue, they likely didn't properly center the wheel before setting zero toe upfront; it also points to a general lack of care. I doubt your dealer is using a state of the art alignment machine either.

I don't think it's the first time any of us got a subpar alignment from a dealer. I got a cut-rate alignment at an NJ dealer before; shortly after I ran it through another dealer's alignment "scanner" (one of those drive through alignment checkers) and it was way out of whack.

It might be worth a quick stop at an indy who has a Hunter Hawkeye who knows what he/she is doing.

Mr. Turtles

My experience with a 2012 and 2015 with a 991 C2S was that I needed to max out the camber allowed (no shims) which I believe was around 1.5 - 1.8, This helped the tires to last at least 20 sessions (and then some more but not as great) in the Black run group at PCA events. Without the added camber the tires were wearing out almost twice as fast.

Inbyten

This helps. Thanks!

RRDnA

With street tires its important to use the Porsche recommended pressures when at 20 degrees C e.g. start at ~ 32 front ~ 36 rear and then adjust to that range.

If its DE driving, do 5 or so laps, come in check your pressures, adjust - rinse and repeat until pressures are stable.

Inbyten

Yeah, I adjusted such that I was running 33/39 hot. Partial load recommended pressures are 31/38, and full load is 36/44.

My dealer and/or tire rack is saying the tires crapped out because I was running pressures too low. They said I should've run 36/44. That seems like BS to me. Others with the same tires were running pressures similar to me and I ran similar pressures on Pirelli pzeroes last year.