15x8's 5 1/2 will they fit what i want?

That seems like too much backspacing to me. That'll move the tire towards the spring. To put any size tire in there you're gonna have to offset the springs in the very least. Do that and then do some measuring. That's the only way to tell. My duster (which has a bigger wheel well than a dart) fits a pair of 275-60-15 MT drag radials with off set springs and a Centerline wheel. I believe its 8.5 wide but don't know the backspacing. I have about 5/8" to the spring and didn't have to roll the wheel lip. Oh yeah, i have SS springs on it too. Borrow some wheel/tire combos from friends and try them out before you buy something that won't fit.

don