Well since nobody cared to recommend a clear bra cleaner I went and got some purple power (they were out of simple green
It worked good enough but I had to put a fair amount of elbow grease to get the tire crap off the clear bra.
Also, word of advice: Don't use goof off on the clear bra. It turns it yellow right Very fast. Luckily I tried it on a door strip so I just peeled that off. Purple power didn't discolor the bra.