Hey Monty, Welcome.
The standard tire is a 235/75/15 that is about 29 inches tall. What, if any, size larger that will fit without rubbing anything depends on other factors, such as rim width, tread width, and section width.
If you are buying from a tire dealer, they will usually be willing to mount 1 tire and allow you to see that there are no clearance issues.
Good Luck