I've been airing up the tires on my mod IV project since I brought her home last month. They've only been flat for ten years, I can't understand why they keep going flat. I was a little shocked to learn that the side of the tire says "trailer" and that the hub cap has a hole for a grease fitting aka boat trailer! I'm now a little more educated after reading old forums threads, but I'm wondering about replacements. The tire size is 16.5x 6.5-8. I found some nice looking, and affordable, tires from Desser that are made by Nan that are 21/1200-8 2 ply smoothies. They advertise them for the Kitfox. Will they fit is my question. And I assume they will need tubes as well.