On my super bee i have 15 X 10's and 5.5 backspacing mag 500's. I rub on hard corners or going up/down a big hill and slight turn. Dunno how you got around that on the roadrunner. My car has 295/50's (i believe) radial t/a's.

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Just have stock springs on it. Have some ss springs in the shed but have yet to get a chance to put them on.