I had this happen not to long after I purchased my tt used. And remember the previous owner said he had replace one of the tires due to it going flat the previous season. I decided to just replace them all and did so with Maxxis ST's and really like them. They have very small balancing weights to balance them. I try to keep my speeds at 65 or below since I get better MPG. Ordered through discount tire. I also religiously check the pressure before I leave to tow in both directions, and always do at least a visual/ thump test when I stop to get gas.