Backspacing : Distance from the backside of the rim to the mounting surface.
Offset: Distance from the centerline of the rim to the mounting surface. Not sure which way is positive/negative.
and here https://www.rsracing.com/tech-wheel.html
so it looks like between 4.5 and 5" of backspacing, thats kinda high.
but i have 17x9 wheels with 4.5 backspacing (-12 offset) and a 34x12.50 tire and i dont have any problems at all.