I saw the same sidewall issue on my 06 at the beginning of this year but tire tread was like new. I made sure pressures were at the appropriate level but it still blew out on my second trip of the year. The tires also flex alot. Glad to hear that going up to e range helped that. My other concern is how the tires match up to the roadway. My wheels appear to be "bowed out" at the bottom as though there is too much weight on them. I never load up my boat for trips and even try to make sure I have less than a half tank of gas to lighten the load, but it always looks the same. Is that common on a single axle trailer?