Another Backspacing Question

I currently running 15x8 with 5.25 backspacing. No clearancing was needed and no rubbing issues with my 26x10.5 drag radials (10.5" at the widest section width).

I want to buy another set of rear wheels to put some regular tires on, and would like to go with a 15x10. I see 6.25 and 6.5 back spacing. I know I will have to roll the fenders and massage the inners. Effectively I will be adding 1 to 1.25" of wheel to the outside edge of the wheel well.

My question is this: how much does the rim width affect the tire width? Meaning, I can squeeze a 275 tire on my 8" rims, but how much wider will that tire get going on a 10" rim? I have a hard time looking at the edge of my current tires and thinking that there is room for another 1.25". But I may be confusing the point, and the tire may only grow a small portion.

Can someone give me some real world experience here? Also, 6.25 or 6.5" fit easier with a 10" rim?

Thanks.

Joe

Gear grabber said:

I understand what you are asking,but it is hard to say how much wider the sidewall will get on a 10'' rim v 8''.
Shorter tires are easier to fit then larger. Typical 275/50-15 will probably be fine on 6.25 or 6.5 B/S. When tire width and diameter are pushed to the limits,B/S becomes more critical.

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I guess my big concern is whether or not the tire would grow 1.25" out as well. I believe it will not, just looking for some reassurance I guess.

Thanks for the replies.

Joe