Originally Posted by unitlink
So I'm wanting to create some cribbing for our 5th Wheel since our drive slopes downward a bit. The legs have to be extended pretty far and I think I would feel better if I had some cribbing to place underneath.
The OP was asking about a sloped drive.
I suggest you take a 2 foot long level to the drive. Place it on the drive, under a jack, running the long direction of the RV. With one end on the ground, measure the height of the other end when level. Assuming 6" over 2 foot, you have a drop of 3" per foot.
Take a 2X4 one foot long and mark it for a diagonal cut, 0" at one end and 3" at the other end. Cut along the line. Make several of these. Put together with the cut edge on the driveway, the top should be level. Several nailed / glued / screwed together will make a solid, level base for your cribbing. If the drop is greater than 3 ½", use wider lumber.
I would suggest the cribbing height be about level with your tires, so the jacks are extended about the same distance they would be on level ground, assuming this is low enough to comfortably unhitch from the truck.
Use treated lumber and treat the cut edge to slow rotting and make them last longer