As much work as it may be... take the tire and wheel off and set it flat on the ground mix hot water and liquid soap with a reasonable ammount to help detect the leak. Pour/spray the mix anywhere where the tire wheel come together or places that must seal. If nothing is easily seen let is sit and come back. Foamy bubbles will help point out the leak. Since we cannot see the wheel type you may need to flip the tire/wheel over and apply to the opposite side if do not detect a leak. When you tightened the combat wheel did you use the same method you use when tighting lug nuts? 12,6,3,9, oclock? When doing hummer wheels I often just tighten all snug then toque down from there to keep the o ring from squiring out.