The wheel wells on my 1999 3326K look large enough to put 14" tires on the trailor. It now has 13". The 14" wheels only cost about $25-35 apiece. I often tow at high speed for long distances (75 MPH) and my 13" Goodyear tires are cupping. I bought used so it may also be caused by low presure at some earlier time. What size 14" tires does the factory use on some models? Is this a bad idea. The extra height won't hurt as the trailer is a little low for my truck.