Short answer
Bobtail means a semi tractor is driving with no trailer attached. It happens after a driver drops a trailer, while heading to hook a preloaded one, or on the way back to the yard. Bobtailing differs from deadheading, which means pulling an empty trailer. Bobtail time still counts as driving time under hours-of-service rules.
When trucks run bobtail
- Drop and hook. The driver drops a loaded trailer at the receiver, then drives the tractor to another yard to hook the next trailer.
- Power-only loads. The carrier supplies the tractor and driver, and the trailer belongs to the shipper or broker. The truck often bobtails to reach it.
- Drayage. A dray driver may bobtail to a chassis pool or terminal before picking up a container.
- Shop and home time. Tractors bobtail to maintenance or home when the trailer stays at the yard.
Some people also call a straight truck, like a propane delivery truck, a bobtail. On a load board or in a check call, it almost always means a tractor without a trailer.
Bobtail vs deadhead
| Bobtail | Deadhead | |
|---|---|---|
| Trailer attached | No | Yes, empty |
| Typical reason | Dropped a trailer or heading to hook one | Driving empty to the next pickup |
| Paid by the load | Usually not | Usually not, unless priced into the rate |
| Counts as driving time | Yes | Yes |
| Handling | Light rear end, longer stops | Empty trailer, sensitive to wind |
Driving time definition from 49 CFR 395.2. Braking note from the California DMV Commercial Driver Handbook.
Hours of service and personal conveyance
Under 49 CFR 395.2, driving time is all time spent at the controls of a commercial motor vehicle in operation. A tractor with no trailer is still a commercial motor vehicle, so bobtail miles count.
Drivers sometimes log bobtail moves as personal conveyance, which is off-duty time. FMCSA’s personal conveyance guidance says that doesn’t work when the move serves a business purpose, and it names bobtailing to retrieve another load as an example of what isn’t personal conveyance.
Why it matters to brokers
A bobtail truck near your shipper still needs a trailer before it can load. Confirm whether the carrier has a trailer, where it is, and whether the driver has hours left before you book.
On power-only and drop-trailer freight, the bobtail leg is part of the job even if no one pays for it by name. Carriers price it into the rate, the same way they price deadhead miles.
Safety matters too. The California DMV’s commercial driver handbook warns that bobtails take longer to stop than a tractor-semitrailer loaded to maximum gross weight.
Example: the bobtail leg on a power-only load
Example, with illustrative numbers. A power-only carrier drops a loaded trailer at a distribution center, then bobtails 18 miles to a shipper’s yard to hook a preloaded trailer.
Those 18 miles earn nothing on either load, and they come out of the driver’s 11 hours of driving. If the carrier asks for $60 more on the next load to cover it, that’s the bobtail leg showing up in the rate.
Common mistakes
- Logging a business bobtail move as personal conveyance.
- Assuming a leased owner-operator’s coverage applies while bobtailing off dispatch. Policies differ, so carriers should read theirs.
- Booking power-only freight without the trailer number, yard location, and hook time on the rate con.
- Treating a carrier’s “truck is empty nearby” as a trailer ready to load.