I bought a 734B about 1 1/2 years ago, but lots and lots of work into it, and lots of $. I recently bought a S160 and will sell the 743B in the spring. The 743B has the wide 12" tires (back ones polyurethane filled), in great condition. The front tires are also 12" wide about 1/2 tread left, but they are 1/2" taller diameter than the rear which have almost new tread. The S160 has 10" wide tires in very good condition, at least 3/4 tread left and they are all polyurethane filled. I'm thinking I should put the wide tires from the 743B on the S160 as I do use it on the grass and want to reduce the damage as much as I can. I would then put the tires from the S160 on the 743B that I will sell. How bad would it be to have the 1/2" diameter difference from front to rear tires, I know it must stress the chains. I run on dirt and grass most of the time but some on pavement. Sorry for the long question.