Basic Control: Backing, Turning, and Stopping Distance
Basic Control of Your Vehicle covers low-speed maneuvering - backing, turning a long wheelbase, and knowing how much room you need to stop.
Backing
- Back slowly and in a straight line, using both mirrors, not one.
- Get out and look before backing whenever the situation is unclear.
- Back toward the driver's side when you can, so the trailer stays visible in your left mirror.
- Use a helper and agree on hand signals first; stop immediately if you lose sight of the helper.
Turning
- Right turns: swing wide, but not so wide that a car slips into the gap on your right.
- Off-tracking: the rear wheels follow a shorter path. A usable rule of thumb is about one foot of cut-in for every ten feet of wheelbase.
- Watch the trailer's rear wheels in the mirror through the whole turn, not just at the entry.
Stopping distance
Total stopping distance is perception distance plus reaction distance plus brake lag plus actual braking distance. At 55 mph you cover roughly 80 feet per second, so brake lag alone - about three-quarters of a second with air brakes - costs around 60 feet before the brakes even engage.
Worked example
A combination has a 45-foot wheelbase and turns right into a driveway. One foot per ten feet of wheelbase predicts about 4.5 feet of off-tracking, so the trailer's right rear tires will run well inside the path the cab took. You start the turn from farther left and check the right mirror for the trailer tires clearing the curb.
Traps that cost marks
- Believing a wide swing guarantees clearance.
- Backing with one mirror or with no spotter.
- Ignoring brake lag when judging a following gap.