vette ruminator

I installed MPSC ZPs for my ZR1 and love their grip on the track and they get me to and from events. After using MPSCs on my Z06 without enough camber and getting excessive outer wear, I took a combination of advice from Michelin and forum members with my MPSC ZPs to try to get the most out of this set.

I'm running -2.0 in front, -1.5 rear with the Pfadt camber kit, and -0.02" toe in front, 0.10" toe in rear (reading off alignment sheet).

For the rear tires, pressures were 28 cold to 35-36 hot and the wear pattern on the rear is very even after 4.5 hard days (4-6 20-30 min sesssions) at Autobahn CC (which is very hard on tires and brakes) plus a 1/2 track day on the rain, plus going to and from the track:





The rears are at the wear bars but they are not corded and I may run them again; the stick is still decent even though it is diminished over new.

The fronts are a different story. My goal was to maximize tire life with -2.0 and using Michelin recommended cold 25 hot 32. I saw more wear in the inner and outer tread compared to the middle so I then started 27 cold 34 hot, but after the use as described above the tires are trashed with the inner, heavier treaded area of the tire being wiped clean. Even though they are not corded, there is no more usable inner tread and a spin convinced me they were truly done:







I finished these off at Katech Track Attack (a seriously great time, see other threads), and the guys at Pfadt were there. I showed them the fronts and they thought the toe could be a problem but we got out the toe plates and he concluded that the toe was fine.

If I want to improve the front wear pattern on the next set, should I

A: decrease the front camber to maybe -1.7 or so
B: use higher cold temps to get the middle tire pressure up and even out the wear
C: pump up the cold pressure to 34 or so when not driving on track to compensate for the inner wear
D: drive to and from the track on PS2 fronts and stick the MPSC fronts in the car
E: do nothing, this is the wear pattern of these tires and just buy another set and drive them till the inner tread is bald again. I'm lucky I got 4.5 days out of them...
F: other ideas?

Re: the rears, would you use fresh fronts with rears that look like this? I hate to unmount >$578 tires that still have another day or 2 left in them

Thanks for the advice!

Sidney004

I have no personal experience with MPSC's but 4.5 days at 4-6 sessions a day is nothing to complain about. I would not adjust pressures higher nor reduce negative camber; reducing grip is never the correct solution. The thread patterns are typically asymmetrical to enhance wet weather running; check with Michelin to see if you can flip the tires, that would even out the wear pattern.

VicCaerter

If you flip those tires, that could get quite nasty in the wet. How many street miles are on these?

For starters, I would definetely air up to a min of 35# for street use based upon the pics.

flangley

What size tires r u running front and rear?

vette ruminator

To my knowledge the MPSC Zero Pressure run flats only come in stock ZR1 sizes; I believe they are 285/19 front 335/20 rear

Pumba

For starters, I would change your front toe to 0.02" in.

When I look at your front tires I see the outer edge more worn than the inner edge.

Am I correct?

If so, why wouldn't you increase your front camber to a negative 2.5 degrees?

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vette ruminator

So you're saying to go from -0.02" in to +0.02" in? It is the inside of the tires that are wiped clean, not the outside, so going with more negative camber should make it worse, right?

Pumba

That's why I asked if my assumption was correct. You did not show us a 3/4 view of the front tire-wheel assemblies, so I could not see which side was which.

VicCaerter

Tread blocks are on the inside.

dfinke23

With the way they are wearing I would go -1.75 in the rear, -2.25 in the front and zero front toe, keep the rear toe and pressures the same.

vette ruminator

I can understand why having zero toe would allow better wear but with the inside of the tires taking the abuse here how would increasing front camber help improve the wear?

mgarfias

Add toe in at the front. Remember its not static toe (on the rack) that matters, its toe while the car is moving. There is a lot of give in the system, even with poly bushings (see that vid LG posted about their spherical bearing kit). Things flex, and your -0.02 front toe suddenly becomes -0.25. Also, street driving with toe out will kill the inner shoulders.

I've gone to a smidge of toe in at the front and it completely made that inner shoulder wear disappear.

steve J06

Agree, have found street wear to be much more sensitive to toe out than camber.

Pumba

froggy47

I'm running -2.0 in front, -1.5 rear with the Pfadt camber kit, and -0.02" toe in front, 0.10" toe in rear (reading off alignment sheet).

Does this mean you toed OUT the front and toed IN the rear?


If yes, then zero the front toe.

BTW that's not bad for how many events plus street use as you describe.

Get a good pyrometer for crying out loud if you are running tires that expensive. Then you are not guessing on a forum as to alignment settings.

flangley

I run non run flat michelin psc front p295/30-18
Rear p345/3019

The reason 295 vs 285. I have tire section width of .7 inch more and 2 lbs less weight, 345/30-19. Only cost $330
I run toe out front my 2012 grand sport with S/C has 666 hsp
I have no wear problems on auto crossing run 34lbs front air pressure

vette ruminator

Thanks for the responses. I plan to have the alignment rechecked and especially look at the toe in front. I will also get a pyrometer and check temps to see if the temps are even...

0Louis @ LG Motorsports

Toe will not affect tire wear, if its in the ball park. Camber trumps toe, with over all tire wear.

1.7* camber is not NEAR enough camber for that tire, on a race track.

You will never be able to have proper tire wear on the track AND the street, with that tire.

0Louis @ LG Motorsports

How did your lap times compare overall?

How many street miles?

I need tire temp data too, that wear is odd, almost like the carcass is buckling under load, but thats just a guess, and nothing more.

The rear needs another .3-.5 camber. The front is just a mess, Its hard to tell. There is a lot of build up that is skewing what were looking at. Ultimately, id get a torch or heat gun and scrape the tread of any track pick up so we can see whats really going on.

Pumba