This could be worth investigating as a possible street tire setup. http://www.minimania.com/web/Item/MMKT2104/InvDetail.cfm
Those tires in the picture are 165/60R12 and the O.D. is smaller than stock. Stock O.D. = 21.134" versus 165/60R12 = 19.795" These will lower your ground clearance by 5/8" and speed up rpm's at any given speed FWIW