Back Spacing calculation

[Bowtie67]

I am not 100% sure and want to be before I order my new rear rims, There will be wheel tubs so inner dimensions not an issue. Frame width is 34"

My outside measurement inbetween the rear fenders (stepside) is 73.25"

Axle width drum to drum is just under 55"

Rims will be 12" wide Tires are 15" wide

73.25 - 2.25 (rounded off) space btween tire & fender = 71" (1 1/8 per side)

71" - 55" = 16 / 2= 8 would mean a 4" BS
4" + 1.5 = 5.5 BS (1.5 is for tire over hang)

Anyone else come up with anything ??

[lolife99]

Just remember that a production 12" rim will ACTUALLY measure 13" from the outside edges of the rim. The 12" measurement is the tire bead surface. I like to take a "know rim",...(like a 15x8 truck ralley) and use it to measure off of. Mount it under the truck, (without a tire), and add or subtract inches to put the wheel where you want it. I hope this helps.

[Hart_Rod]

Pretty good chart on Budnik's website:

http://www.budnik.com/techInfo.asp

[dwcsr]

http://www.earlywheel.com/choosing.html has a simple way to find out what you need down on the bottom of the page