best tires

Depends on what kind or racing you are talking about. I ride some MX and lots of trails (for play; not competition) and am about to install a full set of Maxxis Razr's. I've run them before. Good tire, not uber expensive, and performs well in the woods and on the track. Some people would probably call them a good 'all around' ATV tire. You can get a full set brand new from RockyMountainATV.com, with free shipping, for under $ 300.00.

ITP Holeshots are also a good choice; I've run these before, too, and like them.
 
I run kenda klaws. i like them, but i dont race. i find them excellent for mud, sand, gravel and rock. but im sure ITP and maxxis are better.
 
best tires you can get are hoosiers. but they are about 90$ per tire....

I ran itp quadcross on my blaster and loved them, they are about 60$ a tire now.