Tires Sizes

[wigadore]

This is possibly the wrong place to post this question, but this is the truck I am rebuilding. I am almost to the point where I will have a rolling chassis and I am looking at getting some tires and rims for it to sit on shortly. I see some people put the same sized tires all around and some have slightly larger to much larger tires on the back.

Is there a benefit to having different sized tires on the rear? I would assume these people do not rotate tires much on their project trucks. Then again you may not be putting as many miles on the project to require rotating tires all that often.