I just realized that the back tires on my 66 f-100 are rubbing on the inside wheel well.

If I put these same tires on a rim with less backspace then that should move the inside of the tire further away from the wheel well?

So, if I go from a 7" wide rim with 4.25" backspace to a 6" wide rim with 3.75" backspace then the inside of the tire will move .5" from the inside of the wheelwell.

(I am measuring the removed wheel from the inside bolt holes to the inside bead of the rim.)

That sounds simple, but this is new to me and I just want to make sure I am not missing anything.

I was considering a spacer but decided against it because they may not be safe, or good for the bearings and I want different rims anyway.

I would rather not have to buy new tires and the manufacturer (Michelin) says my tire can fit on a rim ranging from 6-8 inches. I will likely buy a Smoothie or Rallye wheel so I can put a little moon in the middle.

Thanks in advance for your help.

 

You're right. Changing backspacing will move the inside of the rim.. regardless of width.

 

Thank you!

 

No. If you change the width by -1" and the backspace by -.5", the tire will end up right at about the same spot.
The reason is because the cross section of the tire will be about the same for any reasonable rim width for that tire. So if you make the rim narrower, 1" in this case the tire will have to bulge an additional .5" from the rim on each side.

 

Thanks for the info. I see your point. My issue is a slight rub of the rear tires against the inner wheel well. Probably when there is movement from a pothole or something. I think I'll put a thin spacer plate on the back tires for now.

 

I'm running 285/40/17 in the rear with 10" rims.
No rubbing issues. My back space is 4 1/2