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A nail punctured my rear wheel tire today while riding. My question is, how do you know if you need to replace a tire or simply repair it with a tube repair kit?
The hole looks pretty nasty. The cap part of the nail entered the tire, leaving an L shaped hole.
My concern is that water might get into the wheel in wet conditions.
From personal experience, I'd say a larger-than-usual hole in the tire could have these undesireable side-effects:
Most of these somewhat larger punctures damage mainly the rubber and not so much the tire fabric (plies). If that is the case, a simple cautionary patch on the inside (with a regular tube patch) is enough to warrant peace of mind.
If the tire is bulging around the hole when it is inflated at the pressure you use, that is a warning indicating the tire is probably too damaged. A larger or stronger patch might be used inside the tire, and some regular observation to see if it stabilizes or grows is needed, but most probably it would be better to get it off the bike (which is very sad when it is a relatively new tire).
Hope this helps
Generally, if you are using an inner tube in the tire, you should replace the tire if there is more than a 2 millimeter cut in the tire casing. Not in the rubber, mind, but it the threaded cloth casing that your rubber bits are laid on to.
I personally err on the side of replacement rather than risking a serious injury from a blow out at a bad time, so I usually replace when there is a 1mm or larger cut in the casing.
Or if I put a new tube back in, and the hole is large enough to see the tube.
Generally, you repair tubes, not tires. From your last sentence, it sounds like you are indeed talking about the tire.
As it is with the tube, the real answer is "Size Matters". In this case, both the size of the hole and the size (okay, type) of the tire. If I was looking at damage to a road tire "slick", the hole you describe would likely having me change tires. On a cross or MTB tire I might try a repair. In addition to using a tube patch, I'd also glue the "L shaped hole" back together with superglue.
If there's any safety doubt, change tires. The closer to the side of the tire, the higher chance this could cause a lack of integrity while riding.
Never hurts to get a second opinion at your LBS either. Smaller shops will tend to give you a straight answer rather than just going for the sale of a new tire.
Ride Happy!
Always BEST to just replace the tire, but... I have ridden my tires with a gash of an inch or longer. I couldnt recommend it to everyone (legal issues) but I do it all the time. I take an old tube, cut about a 2 inch section out of it (so you have a 2 inch long tube, not just a patch), wrap duct tape around it then duct tape that onto the inside of the tire.
It will poke out the cut a little, but as long as you have a decent tire, your chords will keep it from ripping more.
I've never heard of repairing a bike tire. Maybe if it were tubeless you could plug it, just as you do on your car. But if not...I guess if you're just cruising around town give it a shot. If you are pushing the limits on this thing, buy a new tire. Worst case you blow out and slide under a truck (or into a tree maybe if we're talking mountain biking?). Best case you end up flatting over and over b/c the now non-smooth inner wall of your tire constantly wears down the tube. When inflated, tubes are very thin and very easily punctured or worn through. Dropping $50 on a decent tire might seem annoying, but if you hurt yourself riding on busted gear, you'll regret having 'saved' that money.
My opinion matches zenbike's: when in doubt, replace the tire. My riding is 99% on the road. If your flat is due to a small thorn hole, and you have removed ALL of the thorns, or is a puncture from exposed rim or stem hole burs, you can mitigate those by filing, rim tape, etc. If it is from a nail, tack, or larger puncture (like yours), I feel unsafe letting it ride again - my experience is that it wears another hole in the tube or worse... eventually.
I prefer to retire the tire (sorry, couldn't resist the pun) from outdoor riding and then using it for indoor trainering. While the indoor trainers do wear the tire's outer treads quickly, at least you can get a flat, not worry about falling off, and you don't have a long walk to a replacement.
I am not sure if this is going to be accepted as a comment or an answer, so apologies in advance and any superuser please feel free to amend it appropriately
I had a condition a month ago when I braked hard, hit a pothole, somersaulted on the road, and my inner tube had a proper burst with cracks on my back tyre. I would say replace your tyre, get something like a 1200 mile puncture-proof tyres (Schwalbe ones are good) for about $40 (guess). Living in a country like UK where you can never rely on the weather, I always get my tyres replaces in case I have a nasty crack. Rain will destroy my tyre anyway, so no point using those clever crack-repairing glues. Speaking of which, for cracks like 2-3 mm you can use those glues to do the job. They are not too bad, considering that you are not riding somewhere really really hot where your tyre pressure is also affected by the temperature. If you are in a place where rain doesn't really affect your riding, you could probably get away with it.
My suggestion is "Replace your tyre if possible" because your safety is not bigger than your cash :)
If your bike was a Road bike (can't remember), definitely replace the tyres. Road bikes are different animal and with about 120 psi on on wheels, you don't want a cracked and damaged tyre supporting the super-pressurised inner tube!
If the rubber cut is large, replace even if the inner casing is fine
I just realized I'm really stupid today.
I have a Schwalbe Marathon Plus Tour Hs404 700x40c and it is quite resistant, allowing me to do a bit of gravel in between roads on my touring.
On May 2021, I got my first flat on it. It was a perfectly shaped pointed stone, with a very flat base which managed to make it through. I had ridden a Schwalbe of the same type for about 2 years by then, and I know it was a rare occurrence.
After I removed the stone, it left a cut of about 6mm on the exterior rubber. But the inner casing looked fine, and unless I pressed it with my hand, the cut was not very visible, so I decided to continue riding it.
Then today on August 2021 I was doing some other repair, and I noticed that a another stone was stuck in the exact same place! Luckily this one didn't puncture.
But this drove the message home. So soon after the flat, another stone was stuck in there, and I know that tire is quite resistant.
If there's a significant cut on the rubber, replace the tire, obviously. This one was likely a close call for me getting another flat in the middle of nowhere and spoiling a ride or worse.
The stone before I removed it:
The hole when I'm pushing it open:
The inner casing, apparently intact:
Repair strategies
Criggie mentioned in the comments that it should be possible to repair in some cases, which hadn't crossed my mind, so I had a look for it.
The following video from GCN actually explains how to repair even the inner casing by sewing it, but inner casing repair is not a job that would be worth my time on my 35 dollar tires.
They then repair the rubber cut with a product known as "SHOE GOO", which was originally intended to keep shoes of skateboarders going longer, and is readily available.
I ended up buying this one labelled "Shoe Goo II" (it has to be better than the original one, right??): https://www.amazon.co.uk/Shoe-Goo-Crystal-Permanent-Adhesive/dp/B08P5V9GQV I haven't tested the patched tire on the road yet, but the result seems solid and might actually prevent further stones from sticking in.
Here's how the result looks like, with me pressing to open the cut, and it just did not open. I didn't do a perfect job, added a bit too much of it I think, but I'm guessing the excess will just be scrapped off while riding and shouldn't be an issue.
