Repaired tire. ¿safe?
 

Last week I had a flat after running over a piece of glass. My rear tire (a 700x28 Mavic Yksion Elite Guard) had a cut of about 5mm on the exterior side, and 2.5mm on the interior of the tire. I repaired the tube and got back home, but I was quite sure I could see a bit of tube through the tire (it was not bulging through, but the rubber of the tube was visible with a flashlight).

I needed to use the bike before having had time to buy a new tire (I use the bike for a 35km commute), so I decided to stick a inner tube patch on the inside of it to protect the inner tube, and glued a really small piece of rubber from an old tire inside the cut from the outside side to prevent dirt getting in. Since then, I've done 200km on the tire with no adverse effects. The cut has not grown, the tire has no visible deformation, there were no wires visible in the hole before patching it, the repair seems to be holding up well, and while riding it feels totally smooth... so now I'm thinking if it's really necessary to replace it. But at the same time I'm also wondering if it's really safe to keep running the tire vs buying a new one... the tire is in good shape and almost no wear, so I'd prefer to keep it if possible, but I'm also not keen on the idea of it blowing out at 70kph, or while leaning on a twisty road.

What do you think?

I think that f only for your own peace of mind you should replace that tire. Put the new tire on the front wheel and the old tire from the front wheel onto the back wheel.

Cheers

Are you really riding at 70kph? I can't remember the last time I went over 30mph. Even riding down Mt. Haleakala I didn't go over 35, although I was doing over 50 on Zwift. You are probably OK with it as long as you check it every now and then.

Risk is a function of likelihood and consequence, even with a low likelihood of blowout failure if you are hitting 70kph or high speed "twisty" descents you might want to carefully consider the consequences.

If any of the fabric cords in the tire are affected, I'd replace it. If you must use it, I agree to use it on the rear only.

I once put a similar hole in a brand new $60 tire, and I really tried to save it with a cemented "boot," but after a few days I was just too worried about it. I do a lot of high speed descents, sometimes in traffic, where I live.

If it is cut through so you can see the tube through the body of the tire, the fabric cords which give the tire its strength have surely been compromised, increasing the likelihood of sudden failure. Your tires are the only things between your bike and the road. How much would you like a case of road rash or worse? I would say replace it.

Think of the upside and downside; to me, it favors replacement. Bicycling has enough safety downsides; no sense adding (a potential) one.

Ok. General consensus is that it's better if I replace it, so I'm going to buy a new one. I'm a bit tired of replacing perfectly good tires after a few months... unfortunately my commute involves some roads that seem to have too much debris, or where due to stopped traffic I'm forced to ride on shoulders that aren't as clean as I would like, and tires don't last me more than 9 months. I never managed to replace a worn tire on the road bike since I started commuting with it. And on the old bike I managed to puncture a rim with a nail (never seen that before, and hope that it doesn't happen on my current bike with much more expensive rims). Now you see why I'm so willing to keep the tire rolling...

Yes. Note that I'm talking KPH not MPH. I can ride on the "flats", but I usually prefer to commute using the hilly route that involves some twisty roads, and some fast and steep descents. It's a lot more fun, and after the initial climb it's fast in a addictng way. I don't always reach 70 as it requires quite a bit of pedalling effort on my route, but 65 is a pretty usual top speed on my commute rides.

I had the same thing happen a few years ago. It destroyed the tire and tube but missed the spokes. I filed the rim punctures smooth, replaced the rim tape and the rim has been used for thousands of miles more and is still in service.

For your riding and area consider one of the tough "Touring" tires such as the Schwalbe Marathon or Specialize Armadillo. These are heavy and rather "dead" feeling but are very cut and puncture resistant.

I don't care much about weight, but I care about grip. How do these touring tires ride on fast descents? I would like to avoid this tipes of punctures that mostly happen on the ****ty, heavy traffic, and urban parts of my commute, while being able to have fun at the part consisting of lonely twisty roads and descents.

I have a child and unfortunately have little time for riding now (mostly limited to commuting once or twice a week, and maybe a longer non commuting ride once every two months), so I would like to keep enjoying it as much as possible.

Replace it.

I had a similar situation a while ago, I also patched my front tire with a tube patch from inside, hole of a similar size as yours. Held well for 3000 km, I had even forgotten about it. And then it went boom one day - the hole opened up a bit eventually, enough for the patch to push through it, and we all know what happens next. Luckily I was going ~27 kph in a straight line, so I didn't lose control. If it happened when cornering at high speeds.... don't even want to think about it. In addition, it was a 38mm tire that didn't see pressures above 55-60 psi; a road tire with its typically higher pressures might give out faster and even more suddenly.

From the cheap seats (I'm cheap enough to qualify):

Put that tire on the back and keep riding it. Keep an eye on it, and replace it if a bulge develops at the cut. 2.5mm, less than 1/8", is likely going to hold with the tube patch on the inside. If it doesn't, it'll eventually bulge out and rupture -- you want the tire that might blow out on the back rather than the front for better control if it happens. But it probably won't. I've done something similar, including 40 mph descents every other weekend, and wore the tread down to where I was tired of fixing flats and replaced the tire.

I was already set to replace it after previous comments, but your comment just described my fears. I'm not sure though if the patch would fit through without ripping hald the tire... the slit on the inside of the inflated tire is like 2.5mm long, while its double on the outside, and nearly invisible when the tire is deflated. I was unable to see any fabric coming out of the hole, though I'm pretty sure it has to be somewhat affected.

Anyway, since I lack an x-ray machine to verify the real damage, I think I'm going to replace it and have some piece of mind.

If you intend to continue to use that tire you should reenforce the inside cut with something stronger than a tube patch. Park sells tire "boots" that are much stronger. Here: https://www.parktool.com/product/eme...e%20%26%20Tire

I've successfully used a piece of heavy nylon pack cloth as a tire boot and always carry a couple of pieces on my bike for roadside tire salvage. This can also be a permanent fix.

The cut is 2.5mm on the inside of the tire, but double that on the outside. If it was 2.5mm I don't think it'll be a grat deal... for now there's no bulge or visible deformation at all. I've had tires replaced after bulges appearing without external damage before, and this makes me think the damage maybe isn't that bad. The problem is that I'm not sure, and if it suddenly rips apart and blows out while cornering at hight speed... I simply prefer not to think about that.

General consensus has been that it can't be certain so I'll replace it. I think that 30€ for some piece of mind is not that bad.

If you want to chlorinate the gene pool, go for it!

Another reason to be extra conservative as regards safety, someone else is depending on you.
Tires are consumables and you just have to accept that they will need replacement, whether due to damage or wearout.

A new tire of the same model sells for around 30 Euro.

If you are worried about getting punctures on the same model, then consider buying a different model with better puncture protection, maybe something like Schwable models with Greenguard layer. I've never had punctures with Greenguard layers in the first 2 years (but it doesn't mean that it's not possible). But after 2 years, I slowly start to get some punctures 1 time in every 3 or 4 months.

https://www.schwalbe.com/en/tour-reader/marathon you can find the 28mm version for 15 Euro on the internet. I don't find it in Spanish price search engines. But the German search engines have them very cheap, around 20 Euro plus shipping.
https://www.idealo.de/preisvergleich...-schwalbe.html
IT comes in 25, 28, 32, 35, 38, 47mm sizes, so you might consider a different width.
Here, 15 Euro. Shipping 10 Euro to Spain.
https://www.bike24.de/p11037.html


https://www.schwalbe.com/en/tour-reader/marathon-plus or if you want even more protection. It has a thicker protection layer, slightly heavier and a little more rolling resistance. 22 Euro
https://www.bike24.de/p165567.html

Here, you can try to convince yourself with their promotional video of the blue Smartguard in the Marathon Plus.

Yea, I got that it is kph, that's why I left yours in KPH and mine in MPH. There is no place that I typically ride where it is safe to go that fast, nevermind enough of a downhill. In fact, any steep downhill around here is usually of the type where you use the drops and hold on to the brakes for dear life!

Well, I usually reach this speed on a twisty descent that happens to have a relatively long straight midway through it. The rest of the decent I usually ride between 55 and 35kph depending on the turns. I'm usually a bit faster than cars at this descent, but maybe I have the advantage that I know the road by heart.

I damaged the casing in both my tires on day three of the month long tour last year. I used Park tire boots on both. The rear boot had a wrinkle and caused more flats so I eventually replaced the tire, but I forgot the front tire was booted until earlier this year when I got a (unrelated to the boot) flat. I am going to use my touring bike on the indoor trainer this winter to try and use up that tire, but otherwise I feel it is perfectly reliable.

Having the boot smooth and flat is indeed important as wrinkles or sharp edges and corners will cause flats. The pieces of pack cloth I carry as boots have been trimmed and the corners rounded just for this reason.

Tire boots work and work well. Best boots are made from pieces of old tire. Old sewups are best of all as they are supple and the fabric is going to take glue well. Otherwise lightest tire you can find. Cutting them up is slow work. Inner tube patch is not going to do much.

Boots have to be big enough and they have to stick. If any question about how well it might stick use a bigger boot.

5mm means a lot of cords have been cut. If I booted that at all I'd use a big boot. One big enough it would thump a bit. And I would not be excited about using it for high speed downhill. More like a get-me-home patch.

Good for you for riding at speed. Bikes are great fun downhill.

I have found out that 1/32 gasket material made for pipe flanges makes the best boot. I super glue it and cover it with duct tape. The tape keeps the edges of the boot from fretting through the tube.

I'm using Marathon Plus's since a couple decades, and have had flats as many as before. 3 years ago I had a flat with a near brand new one, just a month mounted, due to a 15 mm sized stone with some sharper edges that cut/smashed itself through the rubber wall in one time (I could feel how the wheel was lifted up then down, only that at the moment I failed to recognize what happened), with the stone "held prison" inside the antileak compound, to then some 500 metres further notice the tires pressure drop. The tire, price 40 euro, was a write off, it was just too damaged.

Last thursday, I had a flat, a small leak, it took 8 km to notice the pressure drop (front wheel so less weight). There wasn't much to see at the surface just a small cut, but there was an entire hole inside the antileak compound and probably some object damaged the inner tube.

Yesterday I purchased a new Marathon Plus, but the moment I paid I already regretted it.
The thing is, before 2016, before this tyre was promoted as "unflattable", punctures>flats required nails either straight in, either in sidewall.
The color of the compound also changed then. I think the new one is easier for bigger objects to enter, maybe it's less dense, I dunno.

And they're a pain to replace. Today I replaced the damaged front wheel tyre with the new purchased tyre. It was a long time ago I did (I'm riding 2+ years with another bike with Schwalbes Super Moto X model), and it took me half an hour to just get one side of the tyre over the rim. The classic lifters all failed - they either broke, bent, or damaged the tyre enough to expose the steel cord (beware rust). In the end, I put a single lifter, just enough lifting the tyre to insert an arm of an inverted small combination plier, allowing enough force exertion to shift it sideways and flip more of the tyres edge over the rim.
To put it back on, one has to start pushing with two hands out air beginning at the valve ending at the opposed side. This way it was fairly easy to flip it over the rim.
And this was at home, sitting, no cold. The flat I had to replace along the road, forced me to damage the tyre in order to get it off.
Now that I found a method (the pliers) it may be easier a next time.
Why on earth they didn't make that steel cord / the diameter a bit bigger, I don't know. Maybe they want people to damage their tyres in order to sell more. :P


Due to the hefty price tag (also my fault, was forced to buy at a local dealer) I decided to try repair the damaged one with liquid rubber and also cover the exposed steel cord with it. I found 3 larger holes in the antileak compound under the rubber wall. I filled these first with molten (soldering iron) nylon thread. Shall see how this works out