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I recently had one of my car tires punctured by a screw. It lost pressure only very slowly, it probably took a couple of days before I noticed the tire was below pressure. The guys from the tire company removed the screw, and then somehow "fixed" the tire. They claim it is as good and reliable as a new tire. I don't know on what that claim is based. My question is: is this indeed true?
The tire was actually very new, I bought it just 2 weeks ago. It's s Continental Premium Contact 2 if that would matter...
I refuse to save money on tires because I believe they play a crucial role in road safety. I am now a bit worried that this fixed tire can cause a blowout more easily.
I am looking for something a little more substantial than your own experience or just "common knowledge". Have any tests or scientific studies been done about this subject?
he'll have put in some rubber with a vulcanizing compound, this will fuse the patch and tire together (exact same principle of bike tire patches), you can't fix worn tread with them
I think noone will be able to answer the question whether your tire (or any other tire according to your description) is as good as a new one. IMHO the crucial point with the safety of tire repaired properly (as e.g. in @RedGrittyBrick's link) is not the repair but other damage that may have happend to the tire because of driving at too low pressure. Technically, that is another question: after driving at low pressure, is the tire still good?
I understand your comment. Nobody will be able to tell whether MY tire is as good as a new one. Then my question is more general: are, supposing the fix has been done properly, repaired tires in general as good as new ones. If the answer is no, then I know for sure that my specific tire at least has a chance of being unsafe, and I can have it replaced by a new one. If the answer is yes, then I can assume that at least I have a good chance of driving around in a safe car. 100% safety does not exist, there are no guarantees. Even a brand new tire can have a hidden defect.
@BaGi: I added an answer, addressing all 3 of your questions. I still think that the answer you had before is all you can possibly get in terms of a sensible answer. If those two answers you have cannot answer your questions, I vote for closing the question as "not answerable".
In the UK (for example), tyre repairs must, by law, conform to British Standard BSAU159f:1990. It is likely that equivalent standards exist in your locale.
Provided that the repair is made to the standard, the tyre will be safe to use.
I imagine the standards apply to normal road use, not when the vehicle is to be used for motorsport or under extreme conditions.
With a bit of searching you can find the results of testing by standards bodies of commercial repair products. For example one tested for 70 minutes at up to 320 KPH (200 MPH) by TUV at the manufacturer's request.
The only reason I haven't voted this up is that it addresses the question "Are repairs safe?" rather than "Are repairs as good as new?" I suspect the repairers overstepped by saying that.
US law is similar. There's also an issue of how big the patch is, I've had one tire deemed non-repairable because the offending object changed it's angle of penetration. The outside hole was small enough but on the inside it was a bit of a slice rather than a simple hole.
are, supposing the fix has been done properly, repaired tires in general as good as new ones. If the answer is no, then I know for sure that my specific tire at least has a chance of being unsafe, and I can have it replaced by a new one.
You are asking three different things, and I think that is the cause of the confusion here.
"As good as new" is something quite different from "safe", and still different from whether replacing the tire it is a good idea.
A repaired tire is usually not as good as a new one. If only for the fact that is has already been a used one before the repair was done. Here's one property that severely suffers by the fact that there has been a damage (although repaired): the price you can get when trying to sell it. Unfortunately, I don't have literature substantiate this claim, but here's an experiment you can conduct:
Buy new tires, and sell them (providing the original bill) in order to determine the market value.
Buy new tires. Drive them for a while. Sell (providing the original bill) to determine the market value.
Buy new tires. Drive them for the same while. Take them off, puncture them with a small hole in the repairable area and have the puncture repaired. This way, the repair does not interfere with safety, and no other damage can have happened. Sell (providing the original bill and the repair bill) to determine the market value.
Surrogate experiment: call a few tire companies and ask them about the price for these 3 categories. Ask also for rationales of how they arrive at their price.
Do not forget to tell us the outcome of your experiment.
However, all this doesn't necessarily have anything to do with the actual safety of the tire. It is like asking wheter a rather new car is as good as a new one after it had an accident and the damage was properly repaired.
Personally, while I have been buying and driving used tires, I wouldn't buy repaired car/truck tires: In order to be OK with a repaired tire,
I'd insist on personally inspecting the inside of the tire.
I'd insist on know the history of the damage and repair
A tire that slowly goes flat is no option.
Points 2 and 3 I cannot possibly check when buying a tire.
As for the safety, let me add to @RedGrittyBrick's excellent answer some further points about tire repair in Germany (which I consider equivalent to the linked UK rules).
First, the repair instructions (the UK ones linked by @RedGrittyBrick, do, too!) include that the person doing the repair has to check the interior of the tire for signs of other damage (as e.g. due to low pressure driving).
It is even possible to repair high-speed tires in certain cases [Ref: no restrictions on type of tire]. However, the possibilities are restricted: only few repair kit manufacturers offer this and only for certain makes of tires (the repair kit has a specification of allowed use).
For the tire workshop, selling a new tire probably means more profit earned in less time. Together with the liability question this is a strong incentive to accept the repair order only if they are absolutely certain that the repair is safe.
So, it is possible to repair cretain tire damages safely. @RedGrittyBrick showed that before already. IMHO you cannot possibly get any further answer to the safety question.
It is easy to find evidence about the danger of improper tire repair, like this. However, I did not find any statistics on the reliability of properly done repair.
To add 3 more data points to the discussion: I've personally been driving 3 tires (light truck 2.8 t, vmax 110 km/h) that had been punctured (by something leaving < 1mm hole) on a parking and have been repaired. I never drove them at too low pressure. I've been driving then something between 25000 and 50000 km thereafter. I have to double-check but I think one of them is still "in service". The others meanwhile were replaced, but their "end" had nothing to do with that puncture or repair.
That is 0 repair-related failures out of 3 cases, which translates to a 95% confidence interval for the true probability of a failure after properly done repair between 0 and 70%. This illustrates that 3 data points do not allow much conclusions. But they are a starting point for collecting more evidence.
Last, but not least, for the third question you ask "Should I buy a new tire?", I recommend quickly calculating how much a new tire costs, and balance that againt the hours you're still going to spend on worrying about the repaired tire. Could it be that the hourly wage for your worries is very low? In that case, you may want decide to buy a new tire regardless of the technical condition of the repaired tire.
I can't see an answer here. The market price is irrelevant if the market is not well-informed. (How do you get better informed? Ask a question here!) Asking the OP to do the experiment is not in keeping with our mission of answering questions, not fobbing them off. The middle section has no references, and doesn't address the question. The anecdotes aren't valued here. And finally, if you did answer the question empirically, the OP wouldn't need to worry, making the hourly wage for worry irrelevant.
@Oddthinking: I didn't mean to use the market price as surrogate of the tire's condition, but as a property of the tire that is affected by a history of puncture (here: even if the tire is/were technically as good as a new one). If there exists at least one property that is affected by the history of puncture and repair, then we can conclude that the answer on whether a repaired tire is as good as a new one is no. Side note: why do you think the used tire market is not well informed?
@Oddthinking: I do see a huge difference between no need to worry and actuall not worrying. And I do not think that an empirical answer can help the OP to decide about a new tire, pls. see my comments to the question.
