I did a lot of research on here and elsewhere on the internet. I got it a tad wrong though ended up using .25" spacer for now. The tires are 275t60r15s. On most duster style bodies with 8" wide rims they will fit snuggly with 4.5" backspace if you have an 8.75" axel and 4.25" backspace for a 8.25 axle. I'm not sure exactly on measuring so I dont want to miss inform you with my guess. I didn't want to wait until the axle was in before ordering so I just did research. If you post it the other section I'm sure someone would be able to help out.