Would 72 studs be good for that sled (500 Indy Classic), he doesn't want any studs on the outside. There is only about 85, to 90 HP, and we have the old studs off my cat (I am in the process of puting new ones on), the old tuds are .875 inches long, an 1/4, or 7mm in diameter. (He doesn't take off fast, and he just wants them to help keep him straight on ice)