The past years it has been only tire size is the rules that is why you seen the super-stock doing better than the modified just because the people in the modified had to go up because of there tire size, but the gave us the new rules a the end of last year. So it has changed a little bit.
Classes:
Pure stock (NEW): this class i like your every day driver. Tires has to be a 33 or under. has to be tagged and insured.
Stock:Tire have to be a 33 or under. tractor tires are allowed. NO NITROUS. origional motor. No body swaps ( Body has to be on the same frame and running gears it came with)
Super-stock: 34 to a 38.5" tires. tractor tires allowed. nitrous allowed. Unlimted engine modifications. Unlimited chassis modification.
MODIFIED: 39 to AS BIG AS YOU CAN FIND

. Unlimited modifications
SPREAD THE WORD! WE NEED AS MANY TRUCKS AS POSSIBLE!