Sometimes RVing can be a drag, especially when you have a long trailer. Skid wheels were designed to prevent trailer drag when traversing steep driveways. When I purchased my second 5th wheel I struggled over whether or not to install skid rollers. I decided to drive around for a few months and see if I really needed them. It turns out I didn't need them.
There are three skid wheel applications: frame mounted, hitch mounted and receiver hitch protectors.
Skid wheels are made using heavy duty metal casters. Paktron Industries makes extra heavy duty casters with a urethane outer coating.The idea of a skid wheel is to prevent the RV from dragging when pulling into or out of a driveway with a steep incline. Instead of scraping the asphalt and ripping off your bumper, skid wheels take the impact and lift up the rear of the trailer, rolling it forward instead of dragging. I discovered that my 5th wheel would clear most steep inclines with about two inches to spare. Had I installed skid wheels (which extend about six inches below the bumper) I would have unnecessarily lifted my RV on many occasions when pulling over driveway inclines.
Here is an example of a frame mounted skid wheel that has been bent. This skid wheel is mounted incorrectly because it is not welded directly under the frame. It is mounted to the side of the frame and crumpled under the pressure.
If skid wheels are installed correctly they can be useful in preventing damage caused by dragging.
Another type of skid wheel is mounted to the receiver hitch (another notorious low spot). These can be especially useful with travel trailers when tongue weight causes the hitch to "dive" when traversing a driveway with a steep incline.
One of the best ways to avoid damage to both the tow vehicle and the travel trailer is to avoid driveways with steep inclines altogether. If you must traverse a steep driveway, do it at an angle and go very slowly so as not to cause the RV to bounce down on the pavement.
Preventing you from scraping by - Jim Twamley, Professor of RVing