my friend needs help on what kind of tires to choose and what size to get. he plans on racing gncc soon and wants to know what kind of tires to get on his 400ex.

 

I razr's, razr 2's, Holeshot HD's, Klaw's, Knarly's are all good tires for XC racing. Some of these only comes in 20's, but 22's would give more clearance for muddy conditions.
Most of the guys that I know that race GNCC love the i razr's, but they tell me they wear rather quickly. Next choice is the razr2's but they are costly. (so is the holeshots) So pick your poision and have fun!!