A rock guard is a common RV accessory used to prevent rocks and chips (usually kicked up from your rear tires) from flying out from under the rear of your coach. A rock guard is the first line of protection for your “toad” (tow car). The rock guard is usually attached to the RV frame in the rear and hangs down, almost to the ground, across the full width of the coach. When not towing, rock guards provide protection to any vehicle following your coach. There are three basic types of rock guards. They are the brush, slit, and solid type.
The brush type… looks like a long thin brush hanging from the coach. It is designed so when fast moving rocks hit the brush, they lose energy and drop.
When the coach is moving, air is supposed to move through the brush but when passing one on the highway, the brush will be blowing back. One negative heard about the brush type is that in heavy, wet snow, the brush may become matted with the heavy snow and, if so, will become a large frozen lump.
The slit type… looks solid when the coach is sitting still. The slits are vertically cut to form 4–5-inch wide “ribbons” of material hanging
down. The slits allow the rock guard to be flexible when leveling and the rear of the coach is close enough to the ground that it seems to mash the rubber. The ribbons also allow air to pass through when the coach is moving. One negative heard about the slit type is that, like the brush type, heavy, wet snow, will cause the rock guard to become matted when frozen.
The solid type… is a heavy, thick, solid, piece of rubber material extending from up, under the coach to near the ground and the full
width of the coach. The solid rock guard simply will not allow any material to pass through. One negative heard about the solid type is that in instances where the coach is leveled (nearly every time you camp), it may seem to bend or twist under the coach when the rear is close to the ground. This will not be detrimental to the rock guard but may appear that way.
We always ask this question in our seminars… If the purpose of the rock guard is to stop small rocks and debris from hitting your tow car, why get one that allows anything to pass through it? We have also heard people claim that the brush and slit type allow you better fuel economy since they do not block the air. However, if any fuel savings exist due to these designs, that saving is likely so tiny it cannot be measured.
Regardless of the type of rock guard you select, consider putting a truck-style mud flap behind each rear dual. These mud flaps are available at reasonable prices from various automotive stores and truck stops. The combination of the solid rock guard and the mud flaps is a great combination for stopping any debris from hitting your toad.
(This suggestion is one of the more than 500 in All the Stuff You Need to Know About RVing (ISBN 156870514-X) by Ronald Jones firstname.lastname@example.org and Robert Lowe email@example.com)