Why are my tyres cracking?

[Zapf]

These are a dual purpose Pirellie MT90 mounted on a 650 single thumper.

I am noticing these cracks in the blocks. should I be concerned about how i am riding them?

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[haydes55]

They look all good to me. Gravel can have sharp edges that start a split, then fast cornering can open it wider. Unless the tire is old, or sits in the sun all the time, it shouldn't have hardened and gone brittle.

[AllanB]

Just ride in the mud more - it fills up the cracks.

[Motu]

You should use tyres, that could be the problem.

[Waihou Thumper]

A couple of cuts, yes..
Gravel and cornering does that and like the rest of the inmates say, just ride...
Nothing wrong here, move right along please...:)

[mossy1200]

A couple of cuts, yes..
Gravel and cornering does that and like the rest of the inmates say, just ride...
Nothing wrong here, move right along please...:)

Think OP is more concerned with the multiple small cracks between the knobs. Easiest to see when expand 2nd photo.
Wonder if the knobs are flexing to much because pressure is to low in tyre.

[Waihou Thumper]

Think OP is more concerned with the multiple small cracks between the knobs. Easiest to see when expand 2nd photo.
Wonder if the knobs are flexing to much because pressure is to low in tyre.

aah, yep, see now. Normal...Had a look at mine, pressures? Think it is flex. These are going to flex no matter what surely?

[mossy1200]

aah, yep, see now. Normal...Had a look at mine, pressures? Think it is flex. These are going to flex no matter what surely?

Not sure. Idd think normal but im not an off road rider.

[Ocean1]

Looks like cold tearing.

Don't worry about it, won't kill you on those.

Maybe choose something different next time if you're going to push it a little on the road.

[R650R]

What pressures are you running? maybe too high.
I have same on front of my DR and they stick to tarmac like slicks, absolutely brilliant for an 80/20 tyre. Will take a pic of mine later.

[R650R]

Here's how mine is looking roughly after 2000km... has been few slow rides lately so not as feathered up as it has been in the past :)
The front tyres on the DR don't really do any work, I find the rubber goes hard/off after about 8000km even though plenty of tread left, well on trailwings anyway.

https://drive.google.com/file/d/0B0NXe246IFdvT1hwbUtPR2hWQ0E/view?usp=sharing

[Zapf]

Here's how mine is looking roughly after 2000km... has been few slow rides lately so not as feathered up as it has been in the past :)
The front tyres on the DR don't really do any work, I find the rubber goes hard/off after about 8000km even though plenty of tread left, well on trailwings anyway.

https://drive.google.com/file/d/0B0NXe246IFdvT1hwbUtPR2hWQ0E/view?usp=sharing

Wow your tires are scrubbing off nicely on the edge...


They look all good to me. Gravel can have sharp edges that start a split, then fast cornering can open it wider. Unless the tire is old, or sits in the sun all the time, it shouldn't have hardened and gone brittle.

sounds like what maybe happening. the tire was made mid 2014 so shouldn't have hardened. But yes have been riding on gravel and fast south island sealed corners.


Think OP is more concerned with the multiple small cracks between the knobs. Easiest to see when expand 2nd photo.
Wonder if the knobs are flexing to much because pressure is to low in tyre.

been running 26 psi front and 30 psi rear. so should be high enough?


Looks like cold tearing.

Don't worry about it, won't kill you on those.

Maybe choose something different next time if you're going to push it a little on the road.

possible.... so that is from riding hard when the tires are still cold?


What pressures are you running? maybe too high.
I have same on front of my DR and they stick to tarmac like slicks, absolutely brilliant for an 80/20 tyre. Will take a pic of mine later.

26 psi front and 30 psi rear. yes they have stuck well and I have not fell off yet :P Have done 4'000km's on them in the south island roads now.

[zoomzoombounce]

Looks very normal to me

[Ocean1]

Looks like cold tearing.


possible.... so that is from riding hard when the tires are still cold?

On modern road tyres, yes, usually because of over-inflation, (doesn't allow the tyre to work and warm up). Not sure that'd apply to those tyres, although I'd be running that rear at closer to 25psi.

Given the size and pattern of the tears I'd lay at least some of the blame on the large and very sharp chip-seal they use down there, it has to put more shear pressure on a smaller area. It certainly wears tyres, I can trash a rear on a trip from Picton to Invercargill and back.

[Waihou Thumper]

I can trash a rear on a trip from Picton to Invercargill and back.

With that orange beast it wouldn't matter what tyres you had....:)
It makes you wanna ride like you stole it!

[Ocean1]

With that orange beast it wouldn't matter what tyres you had....:)
It makes you wanna ride like you stole it!

I haven't had that one down south yet, I was thinking of the Buell. Once I organised new tyres in Invercargill before I left and another time I changed half worn Conti road attacks before I left because I knew they wouldn't go the distance. The PR3 rear on the Ully isn't looking too flash with just 4k on it either...

[R650R]

Wow your tires are scrubbing off nicely on the edge...


Thanks. And today after a pretty decent gravel and road ride 50/50

https://drive.google.com/file/d/0B0NXe246IFdvMW5VYVVzcm5rNHM/view?usp=sharing

And the Shinko E700 on rear

https://drive.google.com/file/d/0B0NXe246IFdvZXNoOUdlN2V3SUE/view?usp=sharing

[Zapf]

Thanks. And today after a pretty decent gravel and road ride 50/50

https://drive.google.com/file/d/0B0NXe246IFdvMW5VYVVzcm5rNHM/view?usp=sharing

And the Shinko E700 on rear

https://drive.google.com/file/d/0B0NXe246IFdvZXNoOUdlN2V3SUE/view?usp=sharing

What bike and what are the tire pressures may I ask?