Changed my tyres to Avon ZZS's and this one is from my spare, the others have zero tread. Tread on this one is 3.7 one side, 2.6 middle and 3.5 on the other side. It had a stone embedded in the tread but it's only as deep as the tread and doesn't go into the tyre itself. You can just about see in the photo to the right of the middle of the tyre on the lower half. I've ran it on track like this for a full day with no issue.

£15 plus delivery

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[Edited on 24/6/17 by stevea]