1997 Jeep Cherokee Front tires wearing unevenly.

Had the tires, shocks replaced and an alignment about 2 years ago. Since then I added some airbags for load leveling. I put a dirtbike on a carrier across the back of my jeep. I picked the kit up from JC Whiteny. Since the kit install, my front tires are wearing un-evenly. Especially the front left tire. If you feel the tire with your hand, the tire feels bumpy. The front right not so much. At this point you can hear and feel that the wheel is out of balance. I realize the problem is probably from the kit I installed. Ever hear of any similar problems? Could you explain why or what mistakes I made to cause this problem. The load leveling kit goes in between the frame and leaf springs. To the rear of the axle. With some common air valves.