are you sure the khumos didn't come like that? i got one of my 225/40/18's and they are the escta supra 712's and they have a little line on them too. i thought the samething but then i saw the new and compared to the one on the car, and it's not my tire rubbing, it's my bumpstops. that might be what your's is doing too.
later

2GNT #1865
2006 Yamaha YZF R6 (Blue/Black)
2005 Honda CBR 600 RR (Blue REPSOL)
2003 BMW 325I Premium/Sport Package
2003 Honda CBR 600 RR (sold)
1998 Mitsubishi Eclipse RS (sold)
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DarkOne> but we all have that inner ricer that is just dying to come out sometimes...