When I purchased my 2014 Marathon, I added new Michelins and had a mobile service provide individual axle weights. It was a quick process and priced reasonably.

While I have a full (and long winded) editorial on this topic at: http://www.gadgetguru.com/proper-rv-tire-air-pressure/ here's the video with the owner of the company who provided this service:



As you know, I'm a rookie and I welcome comments and opinions!