check the tire data for the tire brand, model, and size you have.. the chart will tell you what rim widths they will work on..
typically though, the tread cross section is not the same as section width which is how the tire is sized..
for example;
Firestone TRANSFORCE HT - SIZE: LT9.50R16.5 Specs
rim width bolded, table on web page doesn't carry over very well..
9.5R16.5LT 121/117R E None 3,195 lbs. 80 psi 15/32" 40 lbs.
6.8-8.3" 6.8" 9.5" 7.3" 30.6" 682 CA
this will help you with backspace questions;
How to Measure Wheel BackSpace