I don't like to let my coach sit for more than 6 weeks. We will take it out and at least drive it for a couple hours and run the generator and roof airs on to exersize things. Don't let your tires stand in water and try to keep the sun off them. Do keep them properly inflated and taking a little weight off them (DO NOT TAKE THE REAR WHEELS OFF GROUND) will not hurt but I have never incountered a "flat spoting issue" with our schedule of using the drive train.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7