CRF 150 RB 2009 limited / Blck and white

We ride very tight trails with constant changing ground conditions and always seem to spin the tires on the rimsfrom braking hard as we average 50 - 60 miles per hour . The Rim locks help but we cannot stop it . Also it takes out the inner tubes. Otherwise the valves cupping very bad it is an extreme fast serious bike not for a inexperienced rider a all. In the trails a 250 has to work very hard to keep up .