Since I normally haul 75-80,000 pounds on the highways, it can really slow me down going up the mountains and steep hills. Because the regular traffic can maintain the higher speeds, they sometimes do not realize a big truck is going so slow. I usually put my 4 way flashers on about 40-45mph to let others know I am in fact going slow. The same applies to going downhill. When I have 40 tons pushing me down the mountains, I need to go slow enough to maintain control and let the engine brakes do their job so I do not burn up my brakes.