best way to store tt outdoors and protect tires

I think where the difference of opinion is coming from is "use". Most people don't use their travel trailer as much as a vehicle. So, that is why vehicle tires don't "sun rot". It is because it is constantly being moved and the tires are in motion and not sitting and rotting from the sun. Even if you cover the tires and then don't use the tires for quite some time you'll still have problems with the tires. They can get warped from lack of movement.