So I have an 87 Dodge Quigley 4x4 van with 15x8 steel wheels and some crappy MT's. It looks like all they sell in a 33x12.5x15 tire is a C rated tire. Question is, are these rated too light for a full size van? Trying to stay on budget, but I would upgrade to 16" rims to be able to run E rated tires if it is absolutely necessary. Thanks in advance.