Well the rear tires need to touch, so if blocks are needed yes. The fronts do not really require blocks as the parking brake does not affect the front. I have used block many times when the site is not level side to side to prevent one rear tire from being off the ground.
Can someone explain why you would put blocks under the tires?
The reason is most self leveling systems will only allow a 5 degree offset. Also it has to do with the length of the Ram. My front rams will reach or extend 24" and the rear will only have a 17" stroke. Even through the Ram can pick up 7000 lbs each it is not wise to keep that pressure on them. So you use blocks to level and take the strain off the ram but still be able to use it for stabilization. Depending on the system the only one that I know of is the level up where you can put in Manual mode and raise the one rear side to change a tire. Attached is what the difference in each system used buy FR.
Rockwood #8289 WS 2012
F250 6.0 / Husky 16k
With 4 point leveling system
When not in use, i.e. in storage, if your park on gravel or concrete, I would recommend you put plywood, rubber or vinyl mats under the tires. This keeps the alkali from the gravel / concrete away from the rubber in the tires.
Our previous C class RV experienced tire rot after 4 years, parking in mud. If you want to avoid tire rot, place 2 X 6 planks under all tires, and tire covers all around. We wish we did that before we purchased a whole set of tires due to tire rot $$$$$$$