you can get 9" rims for your blaster with stock hubs. i suggest 18" razr mx tires. i have never been a fan of the common 20" tires. but most other people will tell you otherwise and say go with 20" tires.
18" kenda klaws with 20" hole shot mx in the front i have yfz hubs and wheels all around i mainly ride mine in trails and in my creek witck is mostly rock