supercorsa sidewall cracks

[HARRYFLATTERS]

Has anyone had experience of sidewall cracking on Diablo supercorsa
Ive got hold of a set of used corsas less than a year old, upon close inspection Ive noticed some cracking to the rear sidewalls.
I was hoping to use them for a bit of trackday action but Im a bit worried:(

[CB500Racer]

They have probably been left in direct sunlight, I would source another set of ebay.

[HARRYFLATTERS]

Yeh cant say Ill have much confidence in them ,
Looks like the rubber has gone a bit hard, where the tread joins the side wall.
A bit like a shrinkage crack.

I was hoping to hear that its normal, and ok to use LOL!