I've searched online and can't find anything about anyone else having this issue
ive got some r888r tyres that are getting low now around or just under 2mm of tread left, I'm going to fit new anyway but when I run my finger across the rear tyres I can feel ridges like little hills and holes as I run my finger across it, can just see them to if I get my eye close to tyre
Also not worn evenly over 1mm tread in the centre lower

 

The ridges are usually on the inside and caused because of camber adjustment. If the middle of the tyre is worn more than the outside its because of over inflation......... get a 4way tracking done on the car before fitting new tyres otherwise it will do the same to the new tyres.