Got a set of these to try for our Cup Racer class. We race a low grip carpet-type of surface and tires are extremely important. These are a bit smaller than HPI Cup Racer tires, but normal for M-chassis cars. The grip is fantastic and they even squeal a little if you really push them in the corners. So far I have about 1 hour runtime on them and they are holding up great. You will need a set of foam inserts to use these with best results, I am using Sweep Racing soft inserts.