hhk25

I never know how I should proceed with tires that are showing deterioration on the sidewalls. These are Continental 29er tires and as you can see, the threads are making an appearance on the sidewall. Is the integrity of the tire compromised at this point? The tread area is good.

to boldly go

Hello. It is not uncommon to see the tread area intact while the sidewall is dry-rotting for a variety of reasons including more modern multi-compound tires. I would recommend replacing these tires for safety reasons as soon as possible. Happy pedaling is best achieved when you don't have to worry about your tires blowing out unexpectedly.

If you see threads, replace those treads!
-to boldly go

HillRider

If you feel it necessary to ask, the answer is clear. Replace them. Tire failure is a nuisance at best and a hazard at worst.

Andrew R Stewart 

Yes. Andy

KerryIrons

Maybe it is the angle of the photo but it looks like zero wear on the tread. How long have these tires sat on these rims without being ridden?

Iride01 

I wouldn't replace them for what is on the sidewalls under normal circumstances. However if one of my next few rides is going to be really important to me or is in places I don't normally go then I might replace them. I've never had a blow out that amounted to anything more than stopping the bike and having to fix the flat, walk it home or call for a family member to come get me. Never any indications that I might have been calling for an ambulance trip to the hospital as it seems some fear.

But since you had to ask, I do think you ought to go ahead and change it. You should develop your decision on when to change the tire slowly over time and experience behind you.

Chinghis

Heh, in my case, I never thought to ask until the LBS said, "Hey, your tires are looking pretty worn. You should think about replacing them."

Yeah yeah, whatever!

Last week, for no apparent reason I can see (goatheads, thorns, nails, glass, etc.) my front tube decides to go. Seems that it popped right at the seam, near the valve stem. Really happy that didn't happen about 30 minutes earlier, on the 35 mph descent section of my commute.

And now for the joy of hunting down 26" slicks without resorting to mail order. And tubes.

hhk25

You’re right. Almost no wear. I just bought the bike used so I have no idea how long it’s been sitting. I swapped out the tires.

FBinNY 

I'd probably buy the replacement soon, but put it aside and continue on the existing tire until it shows a more compelling reason to replace it.

When thinking about things like this, I make a decision box to weigh both the risk of an event and the consequences. So consider----

The pattern of "damage/wear/rot" seems to indicate an older tire with the rubber somewhat hardened and ridden at low pressure causing cosmetic cracking at the flex point. In itself, this doesn't matter as long as the body plies are intact, as shown by a tire that spins true, with no wobble or lumps. So, the risk if sudden failure is fairly low, but long term life may be compromised if/when water enters the fabric and damages it. (a slow but very steady process)

That said, even a low risk can be unacceptable depending on the potential consequences, so let's consider ---

Are you riding roads, maybe with long high speed descents? How far from home do you ride, and are you willing to risk a long walk home, however unlikely? Lastly consider managing the potential consequences by moving the tire to the rear wheel, where a sudden blowout (not that likely) probably won't cause a crash. (are you a fairly skilled bike handler?

Throw the above considerations into a box, shake hard, and see how things fall.

FWIW- those of us who are road riders, especially those who use tubulars, often ride on tires far worse that this, and have also experienced very inconvenient blowouts (even on beautiful tires) and we're still here. Stuff happens, and riding always carries some risk.

IMO -- In the scheme of things using this tire isn't unreasonable. but you're the captain of this ship and have to make your own decision.