I took this from the owner's manual for the Sterling All Terrain Roadmaster tow bar. Also checked the Blackhawk 2 and Falcon it was the same.
"Towing with a motorhome-mounted tow bar which has an upward or downward slope puts undue strain on the entire towing system. For that reason, do not tow if the tow bar is not within the ‘Safe Zone’ — no more than three inches above or below level. Towing a vehicle with a tow bar that is not within the Safe Zone will result in significant wear and tear on the tow bar and brackets, significant wear and tear on the vehicle’s suspension and frame, and the eventual failure of the towing system.
To determine if the tow bar is within the Safe Zone — first, connect the motorhome and towed vehicle on level ground. Next, measure the distance from the center of the motorhome receiver down to the ground. Then, measure the distance from the center of one of the base pins down to the ground.
Compare these two measurements. To be within the Safe Zone, they cannot be more than three inches apart if the base pin is above or below the motorhome hitch receiver. See Figure 18. If the tow bar is not within the Safe Zone, you must purchase a hitch accessory to raise or lower the hitch receiver. ROADMASTER has three accessories available — Hi-Low Hitches, Hi-Low Drops, and Dual Hitch Receivers — which will raise or lower the hitch receiver from two to 10 inches, depending on the model. Towing with the tow bar more than three inches above or below level will void the ROADMASTER warranty."
Here is the link to the owner's manual.
http://roadmasterinc.com/pdf/85-3326-06.pdfHere is a link to Hitch Accessories for roadmaster. There are several manufacturers and many suppliers with a wide range of prices.
http://roadmasterinc.com/products/accessories/hitch/index.htmlBarry
