From the linited time I have been allowed to ride my wife's CRF230 I've found, great in mud, good in soft ground but tend to squirm on hard ground.
Apparently these are Brazilian made tyres and come standard on the CRF's. I have to say I've read comments similar to what I've found. They haven't done enough riding to give an idea of how they will wear.
When they need replacing I think I'll try set of MOTOZ tyres. I like them on the 500
Brent