Just wanted to throw this into the mix.
Swapped out the 14 inch Marathons with a Triangle TR645 tire. They are 195R14C load range D types. Date code of 2008. Specs on the side wall are 2057 lbs @ 65 psi. They appear to be just a tad smaller than the Marathons but have more tread on them. In my situation I do not see a down side to that. I am afraid that my test may be more of a stationary type than anything as I have no long trips planned for the rest of this year, but even that data too should be useful. There are a couple of more trips coming up this year of varying lengths but nothing over 300 miles one way. I will post any problems. Thanks to all the members of the board that responded to my requests for information on your tires.