Strange creases on sidewalls of tyres

[Twenty Inch]

Hello

I'm running Schwalbe Big Apple on my Dahon folder. THis morning at the station I noticed that the rear tyre has strange tangential creases on both sidewalls. They emerge from under the rim, and peter out about 1/3 of the way around, in the treaded area. They're between 2 and 3cm apart and as you're looking at the tyre, they go towards the back of the bike.

There's nothing rubbing that could have made the marks and they are remarkably regular. They really look as if the sidewall is creasing at regular intervals. I've never seen anything like it before.

Does anyone know what might be causing this?

Cheers

 

[domtyler]

A picture may help.

 

[Twenty Inch]

No digicam and no possibility to upload even if I had one, due to work IT setup.

Any thoughts?

 

[skwerl]

there may well be something at regular intervals that's inserted in the s/wall for strength. Could be that it's giving the appearance of a crease

 

[Steve Austin]

I used to have some tyres that did something like this. the sidewalls were so thin that they would deform under pressure leaving these strange marks all over the sidewall.

 

[barq]

I had something similar to what Steve is describing happen with some MTB tyres. I was running them at quite a low pressure to get more grip and the continual flexing of the sidewalls as they deformed over objects caused marks like you describe.

 

[Twenty Inch]

I think I've worked it out. As Barq implies, the tyres were at lower pressure than optimal the other day. I've pumped it up and the creases are not developing. I guess it's the sidewall creasing on cornering. Thanks for input.