we use 6061-t6 for machining wheels.. 7075 is overkill and is more susceptible to cracking I think. most blanks are cast And that i must inquire what alloy but the call out is alot different than billet contact out. Rotary forging is a forging technology which employs a combination https://forgiatorim.com/product/blank-ra-slant-price-per-rim/