your probably right on that, I'd bet its a 7" wheel. Speaking as someone who does wheel fullsize rigs and having broke many axle shafts. I'd bet you wouldn't want to go any bigger then a 33" max on the roxor. Being its fairly under powered and someone having a softer foot you might be able to make 35's survive but I highly doubt it. Throw in lockers and a spirited driver and running 33's might be suicidal. I believe the tire on the roxor now is 29" tall so to be totally safe and keeping the stock 3.73's in mind, I'd go with a skinny 32" maybe a 235/85R16. Cheap size and lots of options. With all this being said I'm assuming the axles are just as strong as the early cj Dana 27 axles. The one down side with 235/85's is that most of them are heavier LT tires so it adds weight but the plus side to that is it will stop alot of tire punctures. Or maybe even a better idea would be to goto a 15" wheel where tires are even cheaper and with less wheel, comes more sidewall which is even better.