Yes you can go either way, but it's not as simple as just bolting them on. You need to get the right backspacing so that they clear the brake calipers, and don't stick out to much. You will also probably need to bash your pinch weld down to make more room. The overall diameter of a 245/75/16 is roughly the same as a 31inch tall 15. The advantage is more sidewall for better offroad performance, but you are putting a much heavier wheel/tyre combo on, so this in itself has issues such as wear, and fuel economy, plus you will probably loose articulation, and have to fit bigger bumpstops....you don't get something for nothing. Having played around with a few sets of wheels myself, I am happy to go back to the stock alloys.......just my thoughts.
M.
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