Yeah, don't leave the tires on dirt or bare concrete. Mine is never still for more than a coupla months at a time, so I park the trailer on 2x8 lumber or exterior plywood inside my barn that has a concrete floor. So no danger of the wood getting wet and rotting, then attacking the rubber tires. Then I use the leveling jacs and take the strain off the trailer's suspension. I've never literally put the frame of the trailer on jackstands to take all the weight off the suspension and tires.
But for storage longer than a coupla months at a time, I'd take JohnBoy's advice and park the tires on plastic leveling pads or something similar.
As part of the routine for putting the the RV into storage, or when taking the RV out of storage, I'd service the wheel bearings. Re-pack normal wheel bearings, or lube EZ-Lube wheel bearings.
And the RV battery(ies) need attention too. Best is to install a Battery Tender and plug it in for the long haul. But if you park where juice is not available, then fully charge the batttery(ies) using a 2-amp slow charger, then completely disconnect them. Or better yet, take them home and plug in a Battery Tender in the garage or barn or somewhere.
Battery Tender Plus - Batterytender.com