I have that same problem with my 58 stepside. I have reverse rims on the back which gives the truck a nice apperance but if you load it the tires rub in a curve. I had about 1500 pounds of tile on mine and did a 40 mile trip on the interstate.Running flat out at 55- 60 mph it was ok but sudden turns, you hear the tire rub a bit. Red where does the tubing go , on the rear axel pads?