For any 15/7 rim, you wanna go with a 265/50/15....best tires you can use. They're slightly shorter than your typical stock tire, but they're nice and wide. BFG makes a 265/60 but that's an oddball size and you'll really have to poke around to find'em. Those would be perfect though. The ones i'm talking about are readily accessable at Pep Boys, and they're cheap and still grip reasonably good.
BTW, by cheap i mean the last set i bought were right under 70 a piece...that's not bad, and they took a whole years worth of burnouts before they went bald.