Back spacing

gosh I hate to post a new thread but I can’t figure out if these wheels will fit. It’s 17x8 with a 4.5inch backspacing and zero offset. I’m running icon coils with light racing uppers. 285/75r17’s I’m currently running a 4.75 backspaced procomp wheel and my light racing boots around the ball joint are not less than a fat finger with away from the tire. I thought offset and back spacing are the same thing? Help a dumb ass out please...

 

I have 285/75R17 Ridge Grapplers and also have SPC UCAs. My wheels are 8.5" wide with 4.452" backspacing and I have plenty of clearance. Probably 1.5" between the ball joint and the tire. The 4.5" wheel will definitely fit better than a 4.75".

Backspacing is just the measurement between the wheel mounting pad and the back lip of the wheel. Offset takes the width of wheel into consideration and is the measurement away from zero (middle of the rim). My 8.5" wheels are a -6mm offset.

 

I'm running 16x8 with 4.5bs and was told that they are a great size for 285 by Vin at SCS. I'm running 265/75/16 on them currently.

 

Negative offset moves the wheel out, or decreases backspacing. Positive offset obviously indicates increased backspacing.

I think those wheels will fit well, not sure about the tires. My 16x8 wheels with zero offset barely clear, but they do!

 

That size wheel will fit fine. No idea if the tires will. Back space is the space between the mounting surface of the wheel to the outer lip on the back of the wheel. Offset is the position of the mounting surface on the wheel. So, if the mounting surface is dead center of the wheel, that would be 0 offset. Back space and offset go hand in hand, but are 2 entirely different measurements.