Reduce speed and shift to a lower gear before starting down a long or steep downgrade. If the transmission is not shifted down, the brakes might have to be used so much that they would get hot and no longer work well.

Vehicles with an automatic transmission can tow in D (Drive) but M (ManualMode) is recommended. Shift the transmission to a lower gear if the transmission shifts too often under heavy loads and/or hilly conditions.

For vehicles with a manual transmission, it is better not to use the highest gear.

When towing at high altitude on steep uphill grades, consider the following: Engine coolant will boil at a lower temperature than at normal altitudes. If the engine is turned off immediately after towing at high altitude on steep uphill grades, the vehicle may show signs similar to engine overheating. To avoid this, let the engine run while parked, preferably on level ground, with the automatic transmission in P (Park) for a few minutes before turning the engine off. For vehicles with manual transmissions, let the engine run while parked, preferably on level ground, with the transmission out of gear and the parking brake applied, for a few minutes before turning the engine off. If the overheat warning comes on, see Engine Overheating.