I have a 325/50/15 on the 87SS in the sig and i love the 325mm width,however i have about an 1 1/2 of space between the wheelwell and top of the tire.Would a 28X11.5 tire give me more sidewall?Car is lowered 2 in. already,has a mini tub,frame rail notch,Strange 9in.stock length and a 3:90 gear on a 15X10 Weld.Hope all this info helps.P.S I think a 315/60/15 is too big.