nail in tire

[Drew]

Ended up picking up a nail in drivers side rear. The tires are Michelin cups. The dealership removed the tire from the rim and repaired from the inside.
I'm sure they are fine for the road. Track day coming up, there is still a fair bit before the tread wear bar comes into play. (they have 7k km on them) I think I know the answer, but are these tires prematurely ready for the recycle bin?

 

[Steve M]

On paper, a tire patch should be okay, but the consequences if you are wrong in a track environment would compel me to just replace them.

 

[Drew]

Thanks Steve, I attract drama without trying. I figured as much, but asking never hurts. I've noticed they are slipping sooner than they did a few 1000 km ago.(or maybe I'm just more comfortable on the track and pushin harder)

 

[GTS Bruce]

Picked up one once. Fixed from the inside. Roughed up,vulcanized with a patch and heat. Was told tire drops at least 1 speed rating by the reputable tire place but no guarante so I kept it as a spare. GTS Bruce

 

[Steve-Indy]

FYI....FROM NARRA's 2012 Technical Inspection Form:
Tires - Z rated tires with minimum tread depth 5/32 of inch (exceptions for race tires); balanced with no plugs

 

[hou99gts]

Thanks Steve, I attract drama without trying. I figured as much, but asking never hurts. I've noticed they are slipping sooner than they did a few 1000 km ago.(or maybe I'm just more comfortable on the track and pushin harder)

They will slip more with added heat cycles. I just replaced mine that had 7300 miles on them due to heat cycles, not tread. The safe move would be new tires, especially if it is a track with higher speeds involved.

 

[mjorgensen Woodhouse]

[h=3]Repair of Speed-Rated Tires[/h]Because the tire manufacturer cannot monitor the quality of the repairs for speed-rated tires, once such a tire is repaired for any reason, that area ultimately diminishes the tire's designated speed rating. Although the warranty will cover warrantable conditions unrelated to the repair area, the tire no longer is representative of its original manufactured condition because it has been altered. As a result, the speed rating of the tire is void after repairs have been performed. The tire is capable of running at normal sustained highway speeds up to 85 MPH if repairs are made following RMA Standards. Punctures and nail holes up to 1/4 inch diameter which are confined to the tread area may be patched permanently only from the inside of the tire along with filling the perforation of the tread caused by the nail. NEVER REPAIR TIRES WORN BELOW 2/32 INCH TREAD DEPTH. Some OE vehicle manufacturers do not allow repairs of any kind.


More info:

If you apply a patch over a hole, is that going to perform just as well as the original would have? Obviously not. A hole represents a stress concentrator and even adding more material to "bridge" the hole, doesn't change the fact that there is still a hole there.

So, maintaining a speed rating after a tire has been repaired is a matter of how much risk are we talking about - and there is some disagreement about how to handle this.

There one camp that says that the tire is over designed to such an extent that a single repair doesn't affect the performance enough to be concerned about.

Then there is the other camp that says that since the tire has been degraded, you can't expect the manufacturer to back the product anymore - AND he is obligated to warn users of that fact in ways he would understand - by voiding the warranty and voiding the speed rating.

And, of course, there are in between these 2 extremes.

But this all about risk. You can get tires to perform adequately after repair, but there are 3 things that have to be considered.

1) A certain percentage of repairs will be done poorly

2) Even properly repaired tires have an increased risk of failure.

3) The more highly stressed a tire is, the more likely it is to fail - and a repaired tire is more susceptible to this axiom.

But I think your last sentence is the question you really want to have answered - is it reasonable to expect a speed rated tire to be replaced instead of repaired.

Yes, it is. If you read the insurance policy, I'm sure there is a clause that covers this situation. So even though it might be prudent to replace the tire, the tire shop that sells the policy is only obligated to replace the tire if it is unrepairable (or however it is worded) - and that is the basis behind the policy and how the cost was calculated.

If the policy included replacement of speed rated tires every time they were punctured, the cost would be higher.

So this gets down to what it was you paid for, not the issue of whether speed rated tires can be repaired or not.


*** The repair shop will ultimately be blamed for any failures after the repair so because of that we do not repair high performance tires, only replace them.

 

[gb66gth]

I think MJorgensen get the last word on that. BOOM!

 

[LaViper]

Picked up a nail in my left front tire traveling down I-55 @ 70mph, pulled over smooth & slow. Outer side wall was cut by outer edge of rim. But didn't hurt rim. Tires are about 11 months old. Had to buy new tire. Not a happy camper.

 

[Drew]

New set of cups are ordered. Heading to the ridge raceway in Shelton Washington on the 11 of June. Doesn't make sense to risk an incident for 2% of the cars value that I've already had replaced by insurance once :s

 

[TrackAire]

Mark J pretty much summed it up very well.

Here is my 2 cents, we build emergency tire repair kits for military use, etc. Everybody worries about the tread, but the hole might only be 3/16" in diameter, a very tiny wound in the actual tire tread. If you look at your tires carefully, you might see little chunks gouged out that are actually bigger than the nail hole (you might have depth reading holes that are bigger than your nail wound too). These might be caused from multiple things, rocks, sharp edges on concrete driveway lips, spinning the tires at the wrong time, etc. We often drive on tires like this (even race on them) for many miles with no problem.

The part you have to worry about is the belts. Since modern tires belts overlap, you can actually push a nail through the belts (causing the flat) but if you pull it out and put air back in the tire, drive on the tire the belts tend to work their way back into place. Dangerous situation are wide objects that can cut multiple belts and cause a very weak spot. So in the world of flats, a nice smooth nail is often the best case scenario for repairs.

As long as the repair is in the tread area, I would probably run it on the track. BUT, i would not use an internal patch only. I would use something called a plug patch (looks like an intake valve in your motor). It has a patch on one end an a stem/plug coming out the middle. You install it from inside the tire and the pull the plug out from the outside. So what you accomplish is patching to hold in the air and filling the wound channel so water and road salts can't enter the belt area. The danger with getting water/contaminents in the belt area is rust, belt separation, etc. This can lead to a catastrophic delamination (blowout) which can cause thousands in body damage or a very severe accident.

I've seen many tires (real world and on the track) run at high speeds or carrying tons of weight with actual chunks missing out of them (think bigger than a walnut chunk). I've seen many people haul a$$ at the track on corded tires. As long as the internal membrane is sound and your belts are in good shape, it is amazing what a modern tire can put up with. Also, your Cups are some of the best made tires from a quality standpoint, period.

Cheers,
George

 

[mjorgensen Woodhouse]

The thing I don't like about the plug patch is that when you ream out the hole to get the plug in the tire you are actually damaging MORE belts then just the original puncture. I too have raced on a repaired tire that I patched myself,(not a plug) but as a company I would never do it.

 

[TrackAire]

The thing I don't like about the plug patch is that when you ream out the hole to get the plug in the tire you are actually damaging MORE belts then just the original puncture. I too have raced on a repaired tire that I patched myself,(not a plug) but as a company I would never do it.

Mark,

You're probably aware there are different types of probes. The one not to use looks like a rat tail file (can be viewed at Walmart in the tire fix it area, lol). We use a probe that has a spiral fluting with a very mild twist. This type "pushes" the belts apart rather than trying to bust throught them, possibly cutting belt fibers like the the rat tail type can. The belts with steel wires are pretty tough and it would take a lot of back and forth probing, even with the rat tail file to cut them.

In one project our company was involved with, we were only concerned with emergency tire repairs that could be made with the tire on the rim to get the vehicle quickly out of harms way. Through X-rays we found that pushing the belts apart caused no permanent problems because they would come back together as soon as the vehicle was driven a couple of miles. This also has the added benefit of holding the plug or patch plug in place by pinching down on the plug.

Regarding belt damage from either a nail or actual probing to widen the wound channel, the amount of damage was a micro percentage of the total belt area. Now if you have a large wound channel from say a chunk of metal, etc, all bets are off since we can't tell what kind of belt damage occurred without an X-ray.

Here are a couple more thoughts for those that want to make an emergency repair on a tire so you can get back home (like a Viper with no run flats and no spare):

-In testing tire plugs, we found the ones labeled "Xtra Seal, Safety Seal, etc" that are made in the USA were the best compared to everything we tested on the market. Visually they are the ones that look like big brown furry worms. The ones you often see in a autoparts store are black and thin, made in China and they tear very easily when trying to get through the tread and belts, especially on a high load range tire.

-Like I said in an earlier post, a nail is sort of a best case tire puncture because it often causes the least amount of damage. If you get a flat, find the wound but cannot find any foreign object, be very careful!!. The object might have been very large but because of its shape caused what looks to be a small nail hole in the tread, but caused a large wound in the belt area which may have cut a dangerous percentage of your belts. If you can't pull out the object to examine it, assume the worst case and proceed from there.

-Emergency tire repair cannot be learned from a video, reading a book, etc. The best thing to do is get a used tire from a garage sale, craigslist, etc and practice drilling different sized holes in the tread and plugging it. If the tire is mounted, put in about 20 psi and squirt your repair with Windex to see if you have a leak free repair. If it's still leaking, it's no big deal to push in another plug or 3 or 4 if the wound is that big. Once the Windex doesn't bubble up any more, you've got a good seal. When it comes to tire repair, it's like driving, only perfect practice makes perfect.

-I don't know why, but I have no problem going 140 mph on a properly repaired tire on a road course. But I would never do any mile or high speed runs with a repaired tire on my car. I don't have any proof, but I have a feeling the belts might be getting stretched around a bit a speeds over 150 mph due to centrifugal force. Just watching dragsters rear slicks grow and flex in odd shapes makes me wonder how the heck they don't come apart.

-Emergency tire repairs are just that, a way to get you back to a safe place so the tire can be examined, fixed or replaced by a tire professional.

Cheers,
George

 

[mjorgensen Woodhouse]

Fair enough, thanks for your explanation George.