Today I noticed these cracks in my rear tire. what do you think ?
The tire is schwalbe land cruiser and it's only half year on my bike with less than 2000 km.

Here:

Get some new ones.

Those look bad enough in the photos that I'd replace 'em.

Take it off and look at the cord. If the cord's OK, ride it and put it out of its misery. When the tread is worn, retire it. I would be very surprised if that crack makes any difference at all. (You might want to check it after rides to make sure nothing is lodged in it that will cause flats.)

Ben

Let's ask Sheldon.

Many cyclists waste money replacing perfectly functional tires simply because they're old, or may have discolored sidewalls. If you just want new tires because the old ones look grotty, it's your money, but if you are mainly concerned with safety/function, there are only two reasons for replacing old tires:

1. When the tread is worn so thin that you start getting a lot of flats from small pieces of glass and the like, or the fabric shows through the rubber.
2. When the tire's fabric has been damaged, so that the tire has a lumpy, irregular appearance somewhere, or the tube bulges through the tire.

This is normal flex related checking of the rubber tread, and not an issue in any way. Odds are it lines up with the edge of an under tread belt, and so is a stress point in the rubber.

However, the rubber is only a protective cover for the fabric body plies that are the heart of the tire. So until/unless you also see tread separation, or the tire develops lumps and bulges indicative of a failing structure, ride this until the tire wears out or suffers a fatal glass cut.

Tread separation. OK if you just "putt around" town, but if you EVER go over about 20 mph, better upgrade your life insurance.

When I used to drive a semi, a tire like this was about to "throw a belt". You don't want to know what that was like....

OP's tire is gone bad and he needs a new one. At least, I'd say. But who cares what I think?

No other motor vehicle tire manufacturers or tire shops will tell you that it's safe to use cracked tires.
And probably, no bicycle tire companies either.

If you want to try to save a buck and you think that bicycles are magically different somehow than everything else with pneumatic tires, go right ahead and keep on using it--but a new tire is going to look pretty cheap if you crash because of this and need any kind of medical care.

Nonsense. There's a world of difference between bike and tuck tires.

In any case, stress checking, and tread separation are different and in the case of bike tires, and even non-recapped truck tires, one isn't necessarily an indication of the other. The issue related to recapped truck tires is something different.

The OP has plenty of time to wait until the tread shows signs of actually coming away from the body. Those of us who've been riding "colle a main" tubulars wite thread is simply rubber cemented to the tire body are used to seeing separation at the edges, especially if there was plenty of rain riding, and I've yet to hear of a single case of actual separation happening, not even to a friend of a third cousin. It just doesn't happen except via a long very slow process.

That tire is fine, assuming the underlying cords are not damaged. When deflated, you can flex it enough to see if the cords are damaged inside.
When fully inflated, spin the tire slowly and see if there are any bulges or irregularities in the tire.

Agree that the tire is fine. Could be that the OP was running the tires below the optimal pressure for conditions and load.

That said, if Schwalbe's intent was to design a tire to ensure cosmetic cracking of the sidewalls, they did a very good job (tall knobs, kevlar underlayer, with an abrupt transition to a sidewall with thin rubber).

this is a 1 1/2 hr yr old tire? seriously? that's pathetic

...and yet, there really isn't a lot of difference between a semi tire and a bike tire, aside from size and load. BTW, I was NOT referring to recaps. "Throwing a belt" is NOT the same as "Throwing a cap" (or "alligator"). Circumferential cracks indicate belt separation, followed after some time by belt breakage and 'peelage' (flapping about), whereas radial cracks indicate 'dry rot', which can result in a blowout.

The tire is compromised, and depending on speed and load, you will have to replace it before too long. I would not ride it; I'm not that poor, and I value a tire that I can depend on.

It happens.

Also keep in mind that though it's only 1-1/2 years old to the user, it might be much older in real time, because we never know how long it sat on a hook someplace before he bought it.

Belted tires are prone to this kind of stress cracking of the rubber, especially if there's a big transition in thickness close to the edge of the belt. Weather and UV aging is also a factor as it makes rubber lose suppleness.

Add high loads and/or low pressure which cause maximum flex at the contact patch, and voila. But as I said, it's 95% cosmetic, and odds are that the tire will last long enough for something else to kill it off first.

Make sure to supply your address for his lawyer to find you for the hospital bills and the pending law suit.

There's still a big difference mainly relating to mass and speed. The stresses imposed by a 2" thick tread cap spinning at a constant 60mph dwarf those of a 1/8" cap spinning at a sometimes 30.

Since the bond strength holding tires together is basically the same, it's obvious that the heavier faster mass is far more likely to pull apart than the thin slow spinning mass.

As I said, in over 50 years, I've yet to hear of a single instance of sudden or catastrophic separation of tread in a bike tire, not even a rumor of one. Talk of it is groundless fear mongering.

I'd ride them if the cord on the inside looks good. Keep an eye on them but for a mountain bike it should not be a problem. If it were a high-pressure road bike tire I'd consider replacement though.

He can reach me through the forum.

Actually, while I'm not invested n what people decide, I'd be very happy if the OP kept riding this tire while monitoring it's condition, and reported back eventually with what finally killed it off.

Unless the OP decides to quit sooner, I'll bet 5 beers to one that this tire either wears out, or fails in the typical fashion of cuts or tears due to road hazards.

How about if you'd slather it with liquid rubber, yeah fill in them cracks,,, I'd ride them till they blow up,,

That is just sad from a tire company that usually makes a great tire. Are you checking the tire pressure before each ride? Looks like tires that have been run on low air pressure damage. Anyhow I'd replace the tires pronto. Not worth a blow out and possible crash.

OK, let's assume the worst.

The notion that running a tire like this one references a possible crash. Think about this for a moment. Tires blow out almost on a routine basis. We've had countless reports of blowouts, usually when tires aren't seated properly, here on BF, and most of us that ride light tires have had either blowout, or glass cuts that deflated so explosively that they might as well nave been,

I've been riding tubulars for 50+ years, and instantaneous defaltion is just about the norm, with slow leaks the exception.

So, with this long history of blowouts, how many result in crashes with injury of some kind, or even crashes with no injury.

The simple fact is that anyone who worries about "dangerous" blowouts should give up bicycling while he still can, because no matter how careful you are about tires and rims, they can and will happen.

This isn't to encourage riding tires that are likely to blow at any moment (the OP's aren't), but simply to add some perspective relating to the likely consequences, other than being stranded, which is probably the worst that will happen.

BTW - if I were running a training school for bicycling on the par with some of the serious defensive driving courses offered to motorists, one of the exercises would include unexpectedly shooting out a front tire, so the rider can experience a blowout, and be prepared to handle it.

I suppose the cracks are due to low air pressure on the tire. I usually fill pressure of 50 psi for convenience (I weigh only 60 kg) while the recommended pressure is 55-75psi.
I think I will keep using it (with 55 psi) and keep an eye on the cracks.

Odds are on your side. Chances are you won't crash from a bicycle flat. But after a blowout there is a small chance tire can come off the rim and wedge between fork or frame and lock up the wheel. Very small chance. But not a chance I'd push with splitting rubber on tires.

Just so you realize if the tire rips apart and pops no amount of tubes and patches are probably going to repair tires cracking that much. May get by with a tire boot or dollar bill trick but you may be pushing.