Wizel603

not sure how long this tire has been this way, but I have plans to use this bike later today and I just noticed this tonight and the lbs doesn't open till monday. I normally keep an extra tire around, but this particular rim is too wide for it.



the threads appear undamaged; it's just the rubber that has cracked from age. I will replace it first thing monday, but so far I've never had a tire blow out on me except in cases where the threads have been damaged so I'm wondering just how much risk I'm taking.

if I just ask if I should ride with it this way, I know what the answer will be. I'm more interested in what the chances for the tire may be.

Torchy McFlux

If the casing threads are intact, you're probably fine.
By the way, that's not cracking from age. That's slashing from a knife.

mcgreivey

If it were my bike, I'd probably change it, unless I rode the bike infrequently, or only to run short errands.

In the short run, and for short trips, it should be fine. Keep your eye on it.

If you do long rides away from your neighborhood, you might want to change the tire, or at least bring a spare.

If it begins to bulge or distort, or if it feels at all "thumpy" as you ride, toss it.

Kimmo

If that tyre had full pressure in it when you took that pic, I wouldn't bother replacing it; there's no bulge.

Wanderer

That's not a knife cut! Tooooooo many changes of direction.....

cnnrmccloskey

certainly doesn't look like a crack from age

LarDasse74

If thee is no bulge then it should be OK. That looks to me like the basic $12 replacement tire available from all bike shops and also bike stores. If it si, these tires have a tonne of rubber between the tread/sidewall and the casing. You should be fine until the LBS opens.

Looks like a cut to me, too.

wrk101

Front tire or rear? I would not risk it on a front tire myself. But then, I have N+1, so I would just ride another bike instead.

Jeff Wills

+1 on the knife cut. Age cracks tend to follow the circumference of the tire. That looks like what happens when a bunch of tires are bundled together for shipping and some doofus slices the string holding them together with a utility knife*. As long as the tire cord isn't cut and the tire isn't bulging, ride it.

*Been there, done that, learned my lesson.

garage sale GT

You know, the knife could have cut the cords partially through, meaning it won't bulge but may fail if you hit a bump.

I think the cut would be wobbly if done with a safety razor or small knife. I could see it being wobbly.

operator

There's no partial.

They're either cut or they're not. If they're cut it will show up as a bulge. Which means it's a toss.

Kimmo

Yeah, you'll get a slight bulge even if only a few cords are cut, at least above 70psi or so.

Bianchigirll 

I agree on the knife cut. I would not be suprised if it had been there since the bike was built or the tire unbundled in the shop.

canopus 

Ride it.

FBinNY 

The real test of the integrity of a tire is the shape when fully inflated.

If this is a photo of a fully inflated tire, it's structurally sound and safe to ride. If you want you can put some kind of improvised band aid on the sidewall to keep the weather out of the cords. Ride the tire, and inspect periodically for lumps or distortion indicating that the cords are letting go.

OTOH, if this isn't fully inflated yet and and it gets lumpy at full pressure, it's toast.

garage sale GT

That's ridiculous. Why can't you cut through half a cord? Why can't you weaken a cord as opposed to cutting it all the way through?

Kimmo

Those cords are pretty damn thin...

It's unusual enough to only cut through one ply.

FBinNY 

Of course you can cut partially through a bunch of cords, or cut fully through only a few, as in a glass cut, but either way the test of structural integrity is the same.

If the tire bulges, or twists, or is otherwise deformed at full pressure, the casing is letting go and the tire is toast. Also, like a rope or anything else it's possible to nick or partially cut the casing so it doesn't bulge now, but is sufficiently weakened that it'll fray and let go over time, which is why you have to keep an eye on it.

As far as safety goes, a blowout isn't much worse than the type rapid deflation that occurs all the time on bike tires. There's so much pressure and so little volume that a decent size glass cut, or impact fracture empties the tire virtually instantly, and cyclists have been managing that for over a century.

Wizel603

to answer a few of the questions;
the tire was full pressure (70 psi) when I took the picture, and as far as I can tell when looking at it from different angles there's no bulge. It's also the rear tire, so yes I'm not as concerned about riding it as I would be if it were the front.

the first thing it looked like to me was a knife slash too, but after close examination I grew doubtful. certainly could have been a small surface cut that widened and tore itself longer after the tire aged, which could explain its direction, but the rip overall does not possess anything that has me believing a blade was involved. also the bike hasn't been left anywhere unattended within the past several months where I would even suspect someone would have attempted to damage it. still, I wonder just how long I could possibly have overlooked this, so I'm not ruling out that it happened longer ago than that.

either way, I will replace it soon as tires are cheap and the tire is fairly old. I will be riding it to the lbs when I pick up the new tire though.