ok....

(all stuff listed here is not everything, just stuff relating to this discussion)

Stock class....allows R-compounds. You MUST have the same size (width and diameter) rim though, but it can be any brand or weight rim. Nothing is specified about tire size, so i think you can have pretty much any (except for some picky stuff). you can change shocks/sturts, but not springs.

STS (Street Touring) does NOT allow R-compounds, tires must have a treadwear rating of 140. any size rim up to 7.5" wide. any size tire up to 225. almost any suspension mod is allowed, except for changing of type, which none of us will ever do anyway.

STX - Your spec V will be in this class b/c of the type of LSD you have. a spec V cannot run STS. same mods as STS allowed (tires, suspension)

Street Prepared (?SP) - R-compounds are allowed and pretty much any upgrades you can think of.