Bill Dearborn

I had something similar happen to a rear Cup2 last year. We were running the VIR North Course. Up to that point the Cup2 tires had only been used the first day I took the car to the track. 1/2 of that day was running in the rain and after the rain stopped I put another session on the tires to see what they were like on a dry day.

What I noticed running the North Course is I was getting right rear tire slippage as I crested the fairly steep hill in the right hand turn coming off the Bridge Straight. Even feathering the throttle to keep the tire from spinning as the car went over the crest and followed the turn down a very short straight I would still get a little slippage. In a day and a half that inner section of tread had delaminated from the tire leaving cords there and lots of rubber on either side of that section.

None of the other tires had that wear pattern and the dealer decided to warranty both rear tires because of that wear. I was looking at another member's tires yesterday and after 10 track days all 4 of his tires were delaminating in the same section. From what I have seen and heard from other members we were all running 25 or 26 psi cold temps, had a track alignment and still got uneven tire wear. The off center tire wear reminds me of the old BFG R1 that I ran on my 1986 in the mid 90s that was famous for its Groove of Doom with a similar wear pattern.

Bill

tracer3030

The tech line at Michelin is no help Sent me to the tire rack track site. https://www.tirerack.com/tires/tires...Sport+Cup+2+ZP Not sure why Michelin won't try to help figure out why or what we should do different. Maybe just not talking to the right guy

spearfish25

I just called Michelin and they told me to get it inspected and report back with the result. We'll see how this goes. Last time I tried they just ignored me when I emailed them the inspection result.

spearfish25

There is something very sensitive about that section of the tire. I was at Sebring and there isn't a lot of slow corner opportunity for frank rear tire spin. I only downshift to 2nd in the right hand Turn 7 hairpin and do sometimes get PTM activation coming over the inside curbing. Other than that corner, i can't think of any other place on track where I'm unloading the right rear enough to get significant wheel spin to cause delamination.

I'm no tire guru, but it seems like an intrinsic defect. That entire tread block is just gone and the rubber below is smooth. Looks like it just let go like a retread on a semi-truck. Now I'm going to watch that session on my Gopro and PDR footage and see if I can hear where it happened.

Scr11

This is exactly the wear pattern I've witnessed on my last two right rears at Road Atlanta. I run 27 cold and 34 hot. Something is not right with these tires.

spearfish25

Nothing says ‘grip’ better than when a tire sticks to the road better than itself.

LagunaSecaZ06

I have now switched to MPSS non run flat tires in one size smaller front and back. 275-30-19 and 325-25-20. The car does understeer a lot more than the Cup 2 in stock sizes, however it looks like I can get 6-7 track days (4-5 20 minute sessions per day) as opposed to 2-3 days. I will not set a track record, but the car is fast enough. The car does have a much better ride without the run flats and grip is fine on the street. The MPSS may not be available any longer in the from size due to the introduction of the Pilot 4S. The Continentals in the stock size would probably work as well, when the rears become available. I wish I could afford to go through a set of Cup2 every two track days.

Given the running costs of tracking my 2016 Z06/Z07, I am probably going to buy a C5 Z06 and use it as a track car(drivable not trailer). It just seems to make more sense to buy a salvage title or high mile C5, because I can then run cheaper 18" tires and rims, and the brakes would be a 6 piston 14" iron front setup. I would also not have the fear of an off track excursion wasting my $100K car that is now worth $70K.

nicktenn

Dang that really sucks. I have never had a problem with mine. What was your tire temp and pressure at on the rears?

shizon'00

I'll add one bit to this since it got bumped. A good friend of mine had this happen on his 991 C2S (non run flat cup2). A Michelin engineer happened to be at the track as well and shared the cause they believe is delta T over time. He couldn't share specifics into how long or what deltas were preventing this, but this year, we'll probably take another lap or two to try to warm them up slower. I'll share results.

spearfish25

These sessions my max pressure was around 39 psi. Cosworth said max tire temp was around 200F. Those are upper range of recommended. TireRack and Michelin told me to pound sand.

Mad Dog 24

We've done extensive tire temp \ pressure testing with the Cup 2's. Never any issues with wear and delamination etc. We found optimum max pressures in 36 to 37 range with temps in the 160 to 180 across the surfaces. Never even close to 200. If camber is not set properly to the given track or over driving corners higher temps and pressures with poor wear is a given.

rwheelz

I have had 3 sets these michelins with the same results as the photos here. They simply cannot stand up to hard track use. They always let go on the same tread block, and I tried tracking using both a street alignment as well as an aggressive track alignment.

Poor-sha

I posted this in another thread but I think heat cycling makes a huge difference. I've had a couple of sets where I ran them for a session and then put them away. After that the tires were nearly indestructible and still very grippy.

Mad Dog 24

Agree ^^^ I tracked used Cups with 5 to 8k miles on them. Its crazy how well they last right down to the center cords just starting to show. Never have i trashed a tire because of outside wear!

Rwheelz, Many of us consider the cups are a super tire for wear and grip. If you are killing these tires quickly and delaming i would double check your toe, not the ones on your foot.

3 Z06ZR1

[QUOTE=mallett435;1595310075]Could be wrong but
those don't look like cup 2s's to me!

Newton06

Both of the fronts have delaminated after a hot weekend on VIR North. 3100 miles. The first set had no issues. I will be seeking a full warranty replacement. Hot PSI was good as were temps across the tire width. DSC track alignment.

spearfish25

Good luck. I've tried 3 times with Michelin and Tire Rack.

Newton06

I get these through my local Discount Tire. The managers there have been very helpful dealing with Michelin. If Michekin balks, i will switch to slicks or another brand altogether. These tires should not be exhibiting this behavior.

Mad Dog 24

Just a suggestion since Michelin probably wont be much help. Always put 50 to 100 street miles on new tires. Heat cycles seem to help keep them together for track abuse. I have only notice delam problems once the tire gets worn almost to the cords and even then its very minor. I like to run Cup 2s that have 500 to 1k street miles they seem to hold up for 10 to 12 hard track days, not bad at all!

Good luck

Newton06

Discount Tire FTW!

Both tires being replaced under their road hazard program which I purchased when I bought the tires.

I just have to pay the wear & tear, which came to $171, which isn't too bad for 3100 miles and 4 - 5 DE events.

Both front tires had strips peeling off the second tread block from the inside.

Interestingly, I had no issues with the first set. I got 4700 miles and about the same # of DE events before they ran out of tread.

The *only* difference being I went from DSC's track/street alignment to their full track alignment prior to the last DE.

I am a happy camper.

I will also add that Discount Tire matched the lowest price I was able to find on the internet for the Cup 2s, which was significantly lower that Tire Rack and they got them the next day.

I used to be a Tire Rack customer, but they are now too big, too expensive, and have poor post-sale support. You can't beat a reputable local shop that works hard for your business and stands up for you when things go awry...