I'm running a 190 tire, but on a 6 inch rim. Be warned some 190's are wider than others. This is a Bridgestone BT016, my track has a lot of long right handers. This allows the chain shave on rubber from the tire's edge.
Had the same problem with my KTM Supermoto bike
wjn, you may want to check your rebound in the rear. It looks like you are getting some abnormal rebound wear indicated by the balling up of rubber on the backside of the tread groove and the chamfering on the leading edge coupled with a clean portion before the chamfered portion.
I am ready to switch to the power ones for next season. I've used the DCIII's for the past couple of years and I think I am on the verge of outriding them on the track. One model of the power one claims that tire warmers aren't a necessity and they can be used on road and track. We will see.