Native Nick

I have a 2016 Z06 Z07, which I got at the end of the 2016 run. Being a Z07, it has the Michelin Cup 2 tires. With just under 600 miles on them, the right rear has sustained a puncture from a pretty large bolt. It is almost dead center on the tire. Question is, are repairs to these tires safe up to the Speed Rating of the tire. My last experience with this was a '90 ZR1, and the tire shop claimed an inside patch was good for the speed rating of the tire. Expertise and experience appreciated.

Bill Dearborn

If repaired correctly by a qualified person it is good to the speed rating. Did the tire lose all air pressure? How far and how fast did you drive on the tire after the puncture? If you went over 50 mph or over 50 miles the tires can't be repaired.

Bill

Native Nick

I didn't drive far after the puncture, and didn't know I had a puncture. We've had a ton of rain in northern Cal, which when combined with travel, has only allowed me to take a few quick trips when it has been dry. On a dry day about 2 weeks ago I took it out for about a 40 mile run on a nice road. The car hasn't been run since, and I got a notice from OnStar on Saturday that the tire was flat. I checked Sunday morning, and found it was indeed down to zero, and big fat screw/bolt was pretty much dead center in the tread. I pumped up the tire, and found that 24 hours later it lost about 7 lbs. So, I don't think there was any damage done to the sidewall.

I was planning on taking the Michelin Cup tires off the stock wheels and replacing them with Michelin Pilot Super Sports for street driving purposes. But, I am planning on getting a second set of wheels, and was planning on using the Cup tires for Autocross and Track.

Bill Dearborn

It sounds like all you need to do is to get a qualified repair person to repair the tire. I haven't run patched Michelin run flats on the track but I have run several patched GY EMT tires with no issue. Most track drives aren't getting anywhere near the 186 mph rating the Cup 2 tires carry so some loss of capability won't be noticed. There are only a couple of tracks where speeds get much over 160 mph and even then that is only one straight and only sustained for a few seconds per lap. There are a lot of tracks where the top speed is more in the range of 130 and you can pretty much run an unrated tire at those speeds.

Bill

Native Nick

Thanks for your response Bill. I have been of the same mind that it would be pretty unlikely that on any track I would end up on I would get close to the speed rating. I used to track a stock '90 ZR1, which of course had much lower hp than the '16 Z06, and only was on one track that I could get it up to 130 - Road America Wisconsin on the main straight. Here in California, I will be doing Laguna Seca, and Thunderhill Raceway, perhaps also Sonoma Raceway, and none of them have Straights that would allow me to get up to 186. Perhaps 150. So, I agree a patch should be good.

Always great to get other informed opinions. Thanks again.

Nick

djnice

I self installed a mushroom plug one of my Goodyear's on my ZL1 without removing it from the rim. I have had no issue with multiple track days and speeds to 140.

thebishman

You mention it to be a "pretty large bolt". If so, I wouldn't plug/patch that tyre and use it on a road course. A small nail/screw that is in the centre of the tread yes; but nothing "large".

Tire rack just lowered the price of the MPSC2s, so I'd recommend you just replace it when you also buy the MPSS.

Bish

robert miller

I understand the cost here but if you are going to be running that car in speeds of over 120 mph plus. With what you said a BIG bolt in it NO WAY would I put a patch on the inside of it and hope for the best. Just my 2 cents Now if you keep it below 100 mph you should be able to handle it if it come off and goes down on you. Cause when it does it should do it slow so you can feel it in time. But 120 plus to 150 I don't see it at all and is it really worth it..

Tell you want here OP call and ask a good tire place and tell him what speed you do in your car from time to time. See what he tells you at that point. Robert

djnice

7 psi in 24 hours doesn't sound like a hole that is too big to plug.

Native Nick

Thanks to all for the posts and perspectives. Today I took the Z in for the Michelin Super Sports. Raining constantly, drove down to the best shop in the Bay Area, 15 miles from home. The Cup 2 tires were fine, as I didn't try to push it. As I guess has been reported a lot, the Super Sports were hard to mount on the stock Z06 wheels. However, done, and ride home on the freeway at 70+ mph was a snap. The bolt in the Cup tires was less than suspected. It was a screw with a washer, so the actual hole was about a 1/4", so not a problem to patch.

So have the street tires on (and I hear good performance on track if desired), and have the Cup 2 tires for track. Now, to get a second set of wheels for the Cup tires ...

Thanks again!

djnice

That sounds like a win.

thebishman

Check with House of Wheels for good pricing on the OEM wheels btw.

robert miller

I would feel better about this now with it being a small screw and not a big BOLT that went into the tire. Robert

MSG C5

Good to know. I just took delivery of a 2019 Z06/Z07 and with less than 60 miles, I picked up a nasty screw/nail in the passenger rear tire. I had just picked up the car from my local body shop where I had a custom hood stinger painted on so I probably picked up the nail/screw near the shop as it's located in a pretty industrial area. I was out of town on business last week when I received an Onstar email informing me the tire pressure had dipped to 17 psi. When I got home, I inspected the tire and found the nail/screw. I have a set of Forgeline AR1s and Pilot Super Sports I plan to mount on the car, however I was planning to run the OEM wheels/Cup 2 tires for the first few weeks to get a better feel for them.

It's good to know these tires can be patched so the plan is to remove the wheel/tire and bring it into my local tire shop for the repair.

Custom Corvette Accessories

Lost track of how many plugs/patches in mine...really

They are nail/screw magnets

Can't wait to get rid of those tires...

Regards
Chip

thompstl1

I'd sure love to see something directly from Michelin stating a patched tire held the same speed rating as it did originally. I've sure seen a lot of printed info that states most manufacturers claim the tire has no speed rating, some manufacturers say the rating is dropped to 85 mph. Personally, I'm confused on the issue although I've also heard a lot of people say they haven't had problems after patching.

MSG C5

The Cup 2s really are designed to be driven on a track where there is limited debris. The area where I live is experiencing tremendous growth so there is construction everywhere. Our major expressway interchange is being completely redesigned and expanded and recently while waiting at the very long extended traffic light, I noticed a lot of nails, screws, debris, etc. on the shoulder of the road due to all the truck beds bouncing through the construction zone. Not very Corvette-friendly these days.

Bill Dearborn

The data on Tire Rack's site doesn't specifically address your question. It says Michelin Run Flat tires can be repaired once. On another page it says that non run flat speed rated tires if repaired correctly maintain their speed rating. Nothing mentioned about Run Flat Speed Rated tires. However, I suspect it is the same as the tread portion of the tire's carcass is the same whether the tire is a run flat or not. With the Michelin tires only the inner sidewall is reinforced to permit zero pressure operation. Anecdotally, I have ridden on track on multiple GY EMT Supercar tires that were patched and had no issues at repeated speeds up to 160 mph. I ran the tires until they wore down to the cords and the patch held. What is the worst that could happen, the patch blow out or a section of the tire blow out and let the air out? That could happen with an initial puncture with the types of metal we see on the race track. Cars are always dropping nuts, bolts, screws and pieces of sheet metal. That is also why they are run flats so you can drive on them with no supporting air pressure. As long as the two sides of the tire remain connected by the carcass the tire should hold up until you can get it slowed down and into the pits.

Bill