Both trailer tires are wearing on the inside only. They have about 4000 miles on them. Tires are original that came with rig. Anybody have an idea what I need to do to stop this uneven wear. There is some minor scalaping on the very outside edge of each tire. Tire markings say " max. pressure= 50#. I've been running 38#. Should I go higher ? Have attached photo. Hope it comes thru.