Should we put pads or moisture barriers under tires?
IF it makes you feel better, Go for it,, Else, no..
Based on much reading and research and so on I do not believe it will make any difference, but the cost is very low, so if it makes you feel better DO IT.
The one time I do suggest "Pads" is if you are storing outdoors and put your jacks down over-winter,, Then by all means put blocks or planks or something under the jacks.. here is why
When I went to pull out one January the jacks were not frozen to the wood blocks, but the blocks were frozen to the ground.....
I pulled off.. Went back with my handy dandy 8 or 12 pounder (Forget which think 8) Tapped the blocks just once gently with the 8 pounder (Sledge hammer) and they came free like nobody's business.
The jacks would have been a serious pain frozen down like that.
Home is where I park it!