I will start this post by telling you that I am not a tyre expert. I ha e used a set of ZZS tyres on my 420R since I assembled it last year. My car has now just done 3000 miles.
My car has quite a lot of negative camber, and is primarily used on track. I had a tour to Scotland last week and set off with legal tyres, but half way around Scotland realised that my inside edges on the front were really wearing out fast.
My assumption on excessive wear is either massive long stretches of motorway to get up there from middle England (with mainly the inside edges in contact with asphalt) or the fact that many of the Scottish roads travelled on were a very rough grade (but grippy) surface.
By day 4 of 7 I received advice on here to buy new tyres on here from BMTR, and a day later had them fitted whilst up there. Great service from them (£100 plus vat a tyre) and Pre 3 pm. next day delivery for £25. Also kwikfit were ace.
I told them that I wanted to keep my single edge worn tyres and try and kill them off on another track day.
Now here's the point of my story. I was told by the manager that I wasn't taking them anywhere. He showed me the construction and the amount of rubber left on the edge of the tyres. It was really quite scary. I assumed that there would be some sort of carcasse beneath the tread, but no. The kwikfit guy poked his finger (I kid you not) through the tyre at its thinnest point.
Beyond the tread there is NOTHING left.
Here's a picture of one of the tyres :