we use 6061-t6 for machining wheels.. 7075 is overkill and is a lot more susceptible to cracking I think. most blanks are cast And that i would have to question what alloy but the decision out is alot distinct than billet call out. Are black wheels greater? Black wheels https://blankrimsandwheels60369.nizarblog.com/20124339/slantlip-forgiato-can-be-fun-for-anyone