Wheel size to Tire size ratio for on/off-road use

[KS_Explorer]

I am planning to change the tire size on my rig from 31" to 33". I currently have 15" wheels. I know there will be more sidewall flex, especially when cornering at higher speeds on-road, so I am debating increasing my wheel diameter as well. What is a good range of ratios between wheel diameter and tire diameter when airing down for off-road use? Another reason I am thinking of increasing wheel diameter is that I may want to move up to 35" tires and would like to not have to buy another set of wheels.

 

[DevilDodge]

Most trucks come standard with 18 inch wheels and 20 inch as the option now...and R18 tires are the most easiest to come by because of it.

Otherwise. Nothing wrong with staying with the 15 inch.