I got the ASA ST4 wheels from Tire Rack for my C320. I just got some wheel locks from

http://www.pure-motorsport.com/produ...98/CA=50/PA=10

I got the 12x1.5 Cone Seat 26mm. Is this the correct length? I hear a "very slight" metal scratching noise (not continuous). Is one of the bolt touching something behind the wheel? If so, is it safe to leave it and let it polish off?

Thanks for any help in advance.

Most likely.

Take out one of the stock bolt and compare it to the wheel lock bolt, if the wheel lock bolt is longer, take it to a machine shop to have it cut off a couple mm.

I've compared it with the regular bolts and it's at most 1mm longer. Is it unsafe to leave it and let it wear off? What's the bolt touching underneath?

Cut it down 2mm. It is touching the foot brake, it will damage the foot brake over time, cut it off ASAP.