Specific backspacing question (4.5" backspacing and 12.5" tires)

[jjvw]

Why wouldn't you use washers? It s a 5 minute job to stop rubbing and no ill affects.

Because the mild rubbing on mine occurs at full flex full steering lock at the ends of 12" shock travel. I didn't want to limit steering everywhere to stop one thing that doesn't matter.

 

[HornedToad]

Shouldn’t more backspacing provide more clearance in front of and behind the tire while turning? Since turning will be more of “spin” and less of a swinging back and forth?

 

[Jerry Bransford]

Shouldn’t more backspacing provide more clearance in front of and behind the tire while turning? Since turning will be more of “spin” and less of a swinging back and forth?

More backspacing positions the tire & wheel further into the wheel well decreasing clearance between it and the frame & suspension.

This is how backspace is measured, the yellow tape measure is measuring the backspace dimension which is the distance between the inner-most edge of the wheel and the wheel's mounting flange.

 

[JMT]

Why wouldn't you use washers? It s a 5 minute job to stop rubbing and no ill affects.

Because a little rubbing doesn’t really matter.

 

[Wuqi]

just out of curiosity, what's wrong with running 15x10 wheels?
I've run 33s wrapped around 15x8 for a really long time and they have served me well. I'm currently in the middle of LS swap and I've been thinking about 35x12.5 on 15x10 with 3.75 BS

 

[Jerry Bransford]

just out of curiosity, what's wrong with running 15x10 wheels?
I've run 33s wrapped around 15x8 for a really long time and they have served me well. I'm currently in the middle of LS swap and I've been thinking about 35x12.5 on 15x10 with 3.75 BS

Nothing is wrong with it for a street-only TJ but if you air down much for tougher trails, the narrower 8" wide wheel can more easily hang onto the aired-down tire's bead. A 10" wide wheel requires more air pressure to keep the tire's seated against its edges when it is aired down much. In other words it's more likely for a 10" wide wheel to lose the tire bead than it is with an 8" wide wheel. At least for 12.5" tires. If the tires were wider than 12.5" I'd then go to a 10" wide wheel.