Do your 15x8's have 4.5" backspacing? Do they rub the fender or something else? That size is available in 4 & 4.5" b/s..
I think its 4" backspace. I just have one side that rubs the back of the fender on sharp turns. My tires are 25.5 tall and I have the Guldstrand mod so the extra caster may have something to do with it.