Fuel reaches its destination on one of two kinds of truck, and the gap between them is bigger than most people guess. A transport trailer hauls roughly 7,500 to 9,500 gallons; a typical bobtail carries 2,500 to 5,000. This guide covers what each truck does, the numbers behind the split, and how both fit a jobber's delivery operation.
The two trucks
A transport is a tractor-trailer fuel tanker that runs the high-volume legs, usually from a terminal to bulk storage or large customers. A bobtail is a single-chassis truck built for close-in drops to stations, businesses, farms, and homes.
How many gallons each truck holds
- Transport: roughly 7,500 to 9,500 gallons. Mansfield Energy puts typical legal loads at 7,500 gallons of diesel or 8,500 gallons of gasoline in most states. Confirm limits where you operate.
- Bobtail: roughly 2,500 to 5,000 gallons. Dedicated refined-fuel units sit near the top of that range; many propane bobtails run closer to 3,000.
Weight law sets capacity, not tank size. The federal 80,000-pound gross limit for combination vehicles caps the transport's load well before the trailer runs out of room.
A day's deliveries, by the numbers
Picture a busy station selling 120,000 gallons a month. At 8,500 gallons per drop, that is about 14 transport loads, one every two days or so. Now picture a farm account burning 1,500 gallons a month: one bobtail compartment, on a route with a dozen similar stops. Same product, same jobber, two different trucks and schedules.
When a transport fits
For moving large volumes efficiently: hauling from the terminal to a bulk plant, or big deliveries to high-volume customers. It is the workhorse for the long legs where capacity matters most.
When a bobtail fits
For frequent small drops, or sites a full transport cannot access. Bobtails handle station top-offs, commercial accounts, farm tanks, and home heating oil or propane, where the right load fills a compartment rather than a trailer.
Why the truck type matters
It shapes routing, scheduling, and cost. A transport is efficient for volume but inflexible for small or tight stops; a bobtail is flexible but moves less per trip. Matching the right truck to each delivery is part of efficient routing and low cost to serve. That matching job is where dispatch software earns its keep: FastDragon Fuel Jobber tracks each truck's compartments and capacity so a 14-load station and a one-compartment farm stop land in billing, tax, and inventory the same way.
Common questions
Why do gasoline transports haul more gallons than diesel transports?
Weight. Diesel weighs about 7 pounds per gallon and gasoline about 6.1, so a gasoline trailer hits the same legal weight with more gallons aboard. That is why fuel suppliers like Mansfield Energy quote different maximum loads for the two products.
What is a tank wagon and where does it fit?
A tank wagon sits between the two: a straight truck or small rig under about 6,000 gallons, per Mansfield Energy's market glossary. Jobbers run tank wagons on accounts too large for a bobtail route and too tight or too small for a full trailer.
Do bobtail and transport drivers need different licenses?
Often, yes. A transport is a combination vehicle, so the driver needs a Class A CDL, while a Class B covers most straight-truck bobtails. Both jobs require tanker and hazmat endorsements (combined as the X endorsement) under FMCSA rules.
Can a bobtail deliver to a retail gas station?
It can, and jobbers use bobtails for partial drops and top-offs at low-volume sites. Most retail stations still take full transport loads because freight cost per gallon falls as the drop size grows, so a bobtail run to a station is the exception.
Where does the name bobtail come from?
Trucking slang for a tractor running without its trailer, a "bobbed" tail. Fuel and propane crews borrowed the word for single-chassis tank trucks, and it stuck even though the tank on a delivery bobtail is permanently mounted.