33s or 35s?????

[CW]

You have to remember that a typical 35" tire measurs a hair over 33"s tall, while a swamper will measure close it's stated height. My 36's dwarf my friends 35" BFG muds that measure 33 1/2" tall. If you go with 33" swampers you almost need to consider them as 35's when you choose gearing and axles.

Engine RPM=Gear Ratio x Trans final drive x mph x 336/tire diameter
Just plug the numbers into this and decide what you want. It helps if you look up the actual size of the tires you are thinking about.