A bobtail truck, also called ” bobtailing” or “running bobtail,” is a truck driver term for driving a semi-truck without a trailer attached. A bobtail may also refer to a commercial propane delivery truck specially designed to carry up to five thousand gallons of propane gas for residential and commercial delivery.
- What is a Bobtail Truck?
- Variations of “Bobtail”- More Trucking Terms
- What are Bobtails, Anyway? Origin of Trucker Slang
- Bobtail Insurance, Inspections & Law
- Non-Trucking Definitions for Bobtail
- Is a Bobtail Semi-Tractor Dangerous?
What is a Bobtail Truck?
A bobtail truck is a commercial vehicle or semi-truck driven without an attached trailer. Bobtailing is not preferred by commercial truck drivers since a lack of payload means no product delivery and may indicate the trucker can only collect payment if previously arranged.
Bobtailing is often confused with the similar act of “deadheading.” Deadheading is the act of driving a commercial transport vehicle with an attached but empty trailer.
Variations of “Bobtail”- More Trucking Terms
As it relates to semis, bobtailing was a term coined by truckers. Other bobtail vehicles exist.
Bobtail Propane Trucks
A bobtail propane truck is a commercial propane vehicle specially designed to carry up to five thousand gallons of propane gas for residential and commercial delivery.
These trucks are fitted with a large gas tank to hold their payload and use an attached hose to deliver the gas from the bobtail’s tank to the customer’s. Unlike semis, whose trailers can be attached and removed, a bobtail propane truck has its tank permanently secured.
Bobtail Dump Trucks & Other Small Bobtails
Like a bobtail propane truck, a bobtail dump truck has a permanently secured cargo area. Bobtail dump trucks are classified as “small bobtail trucks,” defined as a vehicle in which all axles on the truck are attached to the same chassis – the vehicle’s frame.
Other bobtail trucks are often used to deliver small loads and goods such as eggs, baked goods, and other delicate or perishable goods.
In some cases, specialty licenses are not required to operate this kind of bobtail truck.
What are Bobtails, Anyway? Origin of Trucker Slang
While the exact origin of the term is unknown, there are a few theories about where “bobtail” may have originated.
Bobtails in Music
Perhaps the most memorable use of this term is found in “Jingle Bells,” a classic holiday tune written by James Lord Pierpont. The song’s lyrics read, “Bells on bobtails ring.”
Pierpont is referencing the practice of “bobbing,” or cutting short a horse’s tail to prevent it from becoming caught in the reins.
Over the radio, truckers often refer to bobtail trucks as “a horse without a wagon.”
Running Bobtail in The Wild
Some narratives suggest the term “bobtail” could originate from nature. Animals like bobcats have short, “bobbed” tails naturally. A bobtail semi with only part of its short chassis sticking out behind is reminiscent of these big cats and their not-so-big tails.
Bobtail Insurance, Inspections & Law
Bobtail driving has been deemed as dangerous enough to warrant its own form of motor insurance. Bobtail insurance aids the driver in the event of an accident while driving without an attached trailer.
Even without a payload, bobtail trucks must stop at all weigh stations as they would if they were making a delivery. Truckers are legally required to stop at all scales unless specifically instructed to bypass a scale or if the weigh station is closed.
When a semi does not stop at a scale, they break the law. If that same truck is later involved in an accident, the driver of the semi will likely be ruled at fault for violating commercial transport guidelines and the law.
Non-Trucking Definitions for Bobtail
As a term with so many variations in the trucking industry, it is no surprise that “bobtail” also has meaning in many other contexts.
Old English Sheep Dogs are sometimes born with a stubbed tail that earned them their nickname, “bobtail.” In the past, bobtail dogs born with long tails had their tail docked — or cut down — into the stubby bob they are known for.
Other animals, such as the Japanese bobtail cat, are further examples of the use of this term to describe the physical characteristics of animals.
Bobtails in Infrastructure
Bobtail bridges, also known as swing bridges, rotate horizontally to allow for the passage of boats. The rotation happens through a center pivot pillar on which the bridge rests. When ships approach, the bobtail bridge rotates, becoming parallel with the shore, opening the channels for ships to pass through. 
Is a Bobtail Tractor Dangerous?
Pulling the weight of a filled semi-trailer may seem intimidating, but it’s a routine task for truckers. Semi-trucks are built with their purpose in mind — to haul heavy loads to a specific destination.
When running bobtail, semis take longer to safely stop when braking at the same rate as a non-bobtailing truck. The truck is not balanced correctly without a trailer, making it front-heavy and more challenging to maneuver. This balancing issue puts bobtail trucks at an increased risk for road accidents.
This risk becomes further exacerbated by inclement weather, improper truck maintenance, and failure to adhere to commercial transport guidelines for both driver and vehicle.
It is important to note that a bobtail propane truck carries hazardous materials. Trucks hauling heavy or oversized loads, no loads, or potentially explosive ones, such as propane gas, all have the potential to be extremely dangerous and can leave devastating impacts in the result of an accident.
Frequently Asked Questions About Bobtail Trucks
Is it hard to drive a bobtail?
Bobtail trucks are often more difficult to maneuver and are more prone to losing control when driving through inclement weather, such as rain or snow. This is due to a lack of balance from the front-heavy cab when the trailer is not connected.
Do bobtail tractors take longer to stop?
Yes. Without a trailer full of product, bobtail tractors become unbalanced and front-heavy. With most of its weight in the front half, bobtail trucks take longer to stop than semis running cargo.