tracer3030

Anyone figure out why this is happening?

LagunaSecaZ06

Happened to mine after 3 trackdays. About 1500 miles in total of street and track. Front right tire below. Left rear looks like yours.

c5racr1

Top picture looks normal for a car with stock is camber. Bottom tires show blisters from overheating the tire. If you are on a left hand track and that is the left front tire and overheated from too much understeer, and too much pressure it looks like that. Cup tires like to be 32psi hot, meaning I usually start around 25-26 psi and give them 2 laps to come up to temperature. That's on my cars, 07Z and the same on my 17 GS. The GS is heavy so u usually start closer to 25psi

c5racr1

On my 07 when I ran cups I would run 2.5 front camber and around 1.7-2.0 rear. On the GS most I have run is 2.0 front and 1.7 rear. I plan on running 2.5 front and 2.0 rear with some r7 Hoosier.

mcoomer

The part you're pointing at is normal for a tire that's gotten hot while being thrashed. It means you've had a bit of fun at the tires expense. Looks like the tire got a bit too hot and started to fail, creating the band that you see at the bottom.

Mike

tracer3030

Tire pressure cold 27psi and before each run. I have 5 track days on these tires 5 sessions 20/25 minutes runs each day. Here's my alignment. 3rd set that peeled and they don't look worn out. Hot they come in front 32-33 psi rear 34-36

tracer3030

I was just pointing out there's still a lot of tread left. I emailed Michelin I wanted to send them the pictures. Michelin didn't seem too interested in the problem. Just said pressure or camber problem probably. Call Sube Sports for information?

shizon'00

I've had two sets do this now after 2-3 track days in hot conditions. Seems to happen after about 15 sessions or so. This is with a few hundred street miles besides the track times.
Lots of tread left on the tires still and they sit at about 34 or so.

Going to switch to slicks for now. I need to do the math on the PS4's to see if the 345 and 295 would be reasonable from a circumference standpoint.

c5racr1

Dude, 15 sessions is a lot. I switched to Pirelli slicks 305/645/18 front on 11 inch wheel and 325/660/18 on a 12 inch wheel. The next size rear is a 705 and it's too tall. If you are running michelins they run differently as far as sizing goes and they run skinny.

shizon'00

I don't think 15 20min sessions is asking too much for a street tire. That's essentially three track days for a DE around here. I would expect closer to 20-25 heat cycles and still never having the tire delaminate, just losing grip or running out of tread. The tires still have a lot of tread when this happens just like the OP. There's something not right with Cup 2's lately.

As far as slicks, it looks like I'm running the same tire/wheel setup as you for my event this weekend. First time on this setup so I'm excited to see what they can do. Need to work my way up to it a little though.

mallett435

[QUOTE=shizon'00;1595309780]I don't think 15 20min sessions is asking too much for a street tire. That's essentially three track days for a DE around here. I would expect closer to 20-25 heat cycles and still never having the tire delaminate, just losing grip or running out of tread. The tires still have a lot of tread when this happens just like the OP. There's something not right with Cup 2's lately.

As far as slicks, it looks like I'm running the same tire/wheel setup as you for my event this weekend. First time on this setup so I'm excited to see what they can do. Need to work my way up to it a little though.[/QUOTE

I agree something does seem different. My front Cup2s were shredded on the outside edges and I'm running 2.5 negative camber up front.

Poor-sha

[quote=mallett435]I still think something is running in your case.

I also think a lot of the delaminating people are saying it's really just pickup. Go drive the car on the street for a bit and look at the tires again.

c5racr1

If you are running -2.5 and killing the outside like that... is it understeering like a tuna boat? Could you be over driving? What track?

mallett435

Yes, it understeered at VIR pretty bad. I have a Z51 with smaller front tires and was pushing it. Over driving could be the issue or too low of tire pressure. I cold start tires around 27 psi. I got down to a 2:07 at VIR and the car definitely needed more grip. More of a concern was my DSC controller was set too soft, so I definitely felt tuna boating a bit. BTW, I love that phrase. Ha! Shocks are much stiffer now, so I'm hoping that solved the problem. Still hard to believe I corded the outside edges on both front tires. I plan to get the alignment checked again, but you can visually see the negative camber is there.

Mad Dog 24

Guys the Cups or Pilots should go thru many street heat cycles before beating them up on the track. This will help delamination in some cases. I see three things that kill tires from a set up shop and drivers perspective. Over driving corners does nothing for time but sure does have a lot to do with tire expense. If the tire is "talking" to you then slip is going on and you maxed out grip.

Not enough negative camber is so common. May I suggest checking tire temps, I bet you will look at your driving habits or camber surprisingly different. BTW All the alignment numbers I've read on the CF and nobody seems to get in the sweet spot that we found, yet. Excessive toe out doesn't help delamination or premature wear either. I haven't seen anyone with printed excessive toe out yet. All I can say is I hope in and effort to finish and get the alignment completed the technician isn't giving some incorrect numbers. Its not that hard to hit print while physically pushing a tire here or there..... get it!

Tire pressures like some have discussed here seem to be to high and could be another cause for delamination. I don't like to see much more than a 7 lbs increase in pressure from cold to hot. For instance we start in the rear at 24 and fronts LT 25\RT 26 on a 3.4 mile course, 11 turns and lots of rights. If my pressures are much higher I'm asking to much from the tires or bring them down.

I just tossed out a great set up Cups'2. Could probably of squeezed another track day out of them but 10 or 11 is very expectable to me and 1 or 2k street miles. That is not short sessions running either many are at least a half hour or more. These tires when set up correctly for the track your running have great grip to their death. I ran a PB just 3 track days ago on them. Many guys would of tossed them. I hope some of our extensive testing will help you guys with tire wear and delam issues on your Z's.

Jetblackc6

Same problem on my last 2 sets. Both sets only having 2 track days each on them and tire rack heat cycling the tires before i mounted them. It is only happening in the wet section of the tire just like yours. they will offer you $50 off your next set for the tire doing this For me i went back to the super sports and have lost little to no lap time and tires still have more then 1/2 tread after 6 track days

Spacewalker

johced1974

[QUOTE=mallett435;1595310075]I have a 2016 C7 Z51 with cup2s and after 3 trackdays, about 12-14 20 minutes sessions my sides were shreaded. I have stock camber/caster. I just handed my car in to get a bit more aggresive camber but I'm sad to hear that your -2.5 still shreads the sides. That sucks.

KnightDriveTV

People try to shave time and they do so by overdriving into turn entry and tearing up the tire, or plowing the entire corner. Then they get slicks to go faster, but never refine the real reason they are tearing up tires and still leaving time on the track. Slicks mask inability.

Gotta be smoother, focus on smoother in, faster out and gathering the car mid turn and generating exit speed, not dive bombing the corner and making the tire earn your way through. Smooth is fast and it'll always be true. I see guys trying to get faster, so they do all their braking later, then jerk the turn in because they are behind the car and still not transitioning off the brake progressively...the compound and the car gets them turned, but the tire sacrifices itself to do it.

spearfish25

Just to further discussion on this, I just had a REAR tire delaminate. Hard to say that's from overdriving corners. Fronts are fine as is the other rear. This one however...not so fine. It let go almost completely circumferentially. It had five 30 minutes sessions on it. I'm over the Cup2s. This bullshit ended my day yesterday at 930am.