[kcchief_fan]

On the left side you can input stuff in inches like 35" x 12.5" tire on a 17" X 9" wheel with 4.5" of Backspacing and it comes up with a number in bold red that will say "no rub", "no rub with a level kit", "no rub with a 6in lift", or "rub". obviously I didn't talk about taking off mud flaps, pinch welds being bent, fiberglass fenders, difference between 4x4 and 4x2 or with or without offroad package as I couldn't find enough data to get that specific. The right side is if your tire is metric i.e. 295/70r17 and offset is in metric i.e. 30mm the wheel size is still input on the left but automatically draws it to the right. I also have a row for original config so you know how your new or proposed setup compares with the final number. That final number is technically the distance (in inches) from the center (x, y and z axis) of your hub outside mating plate to the edge of the tire (outside rear edge) that would hit you back inside front fender. I didn't take into account any deformation of a loaded tire or the oddity in tire size by each manufacture. I just used trig and alegbra to get the theoretically distance and looked at what people said was and wasn't fitting and comparing it to my numbers that were generated. Overall it is statistically close. Backspacing was determined (after looking at a few wheel manufactures that calculate both backspacing and offset for their wheel) by saying that both "lips" on the wheel equal .92". Obviously not every wheel manufacture has the same lip size and that is why backspacing is not the best measurement to use to compare tires amongst manufactures for clearance issues concerning the tires. However it is a great measurement to determine clearance issues with the wheel to stuff like sway bars and knuckles and such.