Tire-sized parking pads

Pardon me if this is answered elsewhere...I searched, but didn't see anything specifically addressing what I am looking for. I need to park my new RV in my back yard on what is now grass. I can't really afford to pour a pad, or put stone down on the whole area. i was wondering if anyone knew of any "parking pads" or "tiles" for lack of a better word. I'm envisioning something maybe 2x2 that I could literally put in front of each tire, and then pull up onto. I realize this won't be a great solution if there's been heavy rain, etc. but this is in high part of the yard, and I've heard just letting it sit on grass isnt the best idea.

Any help would be much appreciated!