The pistons stay inside the cylinders all the time. It's the piston RODS that extend outside the cylinders on hydraulic levellers and that's what developed the corrosion on mine.
The procedure I ended up using was:
Every 2 months, I jacked up each side of the rig in turn so the front and rear wheels on that side were off the ground. I then rotated the wheels by hand through 90 degrees, then lowered the vehicle back on its wheels. Repeat for the other side. After 4 times, the wheels were back where they started. It took about 30 minutes to do both sides.
I didn't have any tire problems in the 4 years we had the coach. The tires were new when we got the coach.
