Whatever you park the RV on, make sure it has a large enough footprint that "it" does not sink in the wet ground (Fall and Spring rains, melting snow). Parking in the grass (dirt) will not hurt the tires, but the weight of the camper will cause the tires to sink in the ground, making it a bit more challenging to get the camper out when the ground dries. And if the ground is still wet, it may be impossible without a tow truck!
When I parked my TT in the grass, I used 10 foot long - 12 inch wide treated lumber for each side under the tires. Those boards DID NOT sink and were long enough I could get a running start and yank the camper through the rest of the grass area without sinking to the hubs.
I have since stopped storing in the grass at my house and decided the mud was just too much ... even with lumber under the tires, and am now keeping it parked on the asphalt part of the drive way.
