I JUST put 15x10's with a 4.5" backspace and 28x10's on, notched to the seam and a rolled lip. There is NO WAY you can remotely tuck the tire with 3.5" backspacing and a tire that size. With 4.5" b/s, if I were to lower my car anymore, it would literally sit on the sidewalls of the tire. I have less than a pinky's width of room.