2x10's sitting leveled from Sept till the end of May every year (thats right 9 months). No cover, just cleaned up and waxed and the tires covered with Princess Auto tire covers. Going into winter 4 with this unit and no tire issues at all. ANd we do get a bit on the cold side here for extended periods.
John & Deb
2011 F250 Lariat FX4 Crew Cab 6.2
2011 Flagstaff V-Lite 30WRLS
Days Camped 2013: 16 2014: 5 2015: 3