By Norman Ford · Updated October 2026
How much does a semi truck weigh?
The ranges in the chart are typical figures for common specs, not limits. A truck's real weight depends on the cab, engine, transmission, axles, fuel load, tires, wheels and options such as an APU. The only number that is exact for your truck is the one on a certified scale ticket.
Semi truck weight limits
Federal rules set the maximum weights for trucks on the Interstate System. Under 23 CFR 658.17, the limits are:
- 80,000 pounds gross vehicle weight
- 20,000 pounds on a single axle
- 34,000 pounds on a tandem axle
- The federal bridge formula for groups of axles, which limits weight based on the number of axles and the distance between them
Source: 23 CFR 658.17, checked October 2026
States set limits on other roads, and some allow higher weights by permit or under grandfathered rules. Our guide to truck weight limits covers axle groups, the bridge formula and state differences in more detail.
Weight on each axle
The gross limit is only half the story. A truck can be under 80,000 pounds and still be illegal if one axle group is over its limit. On a typical five-axle tractor-trailer, weight is split across three groups:
- The steer axle carries the front of the tractor and the engine. Its limit is often set by the axle and tire ratings, which are commonly lower than the federal single axle limit.
- The drive axles form a tandem group with a federal limit of 34,000 pounds.
- The trailer axles form another tandem group, also limited to 34,000 pounds.
Add the three groups together and a five-axle truck can reach 80,000 pounds only if the weight is spread evenly. Sliding the trailer tandem moves weight between the trailer axles and the drive axles; sliding the fifth wheel moves weight between the drive axles and the steer axle.
The bridge formula in plain words
The bridge formula limits how much weight can sit on a group of axles based on how many axles there are and how far apart they are. The idea is to spread heavy weight over a longer distance so bridges are not overstressed. For most standard five-axle tractor-trailers with normal axle spacing, the formula allows the full 80,000 pounds. Short wheelbase trucks, or trucks with closely spaced axles, may be limited to less.
Overweight loads, fines and permits
Running overweight can lead to fines, being held at a scale until the load is fixed, and liability if the extra weight contributes to a crash. Loads that cannot be divided, such as a large machine, can move over the legal limits with permits from each state on the route. Divisible loads, such as gravel or pallets, generally have to be brought within limits instead. Brokers sometimes post loads with weights that turn out higher than stated, so check the bill of lading and weigh after loading.
Empty tractor weight
A tractor's empty weight, often called tare weight, varies more than most people expect.
- Day cabs are the lightest, often around 15,000 to 18,000 pounds, because there is no sleeper.
- Sleeper tractors typically weigh more, roughly 18,000 to 25,000 pounds, depending on the size of the sleeper and its fittings.
- Options add up: a larger fuel tank, an APU, a heavier engine, steel instead of aluminum wheels, and chrome all add weight.
Fuel matters too. Diesel weighs about 7 pounds per gallon, so 200 gallons of fuel adds about 1,400 pounds. Weigh with the fuel level you usually run.
Trailer weight
- 53 ft dry van: typically around 13,000 to 15,500 pounds empty.
- 53 ft reefer: heavier, often around 15,000 to 17,500 pounds, because of the refrigeration unit, its fuel and the insulated walls.
- Flatbeds: aluminum flatbeds can be several thousand pounds lighter than steel ones of the same length.
How weight affects your payload
Every pound of truck is a pound of freight you cannot haul. If your tractor and trailer weigh 34,000 pounds empty, the most you can load and stay at 80,000 pounds gross is about 46,000 pounds, and less if an axle group reaches its limit first. A lighter spec can carry more on every load, which matters for heavy freight such as building materials, liquids or machinery.
Tire and wheel weight
A typical 22.5 inch commercial truck tire, without the wheel, often weighs around 100 to 150 pounds, depending on size and tread depth. A five-axle tractor-trailer has 18 tires in a standard dual setup, so tires alone can weigh well over a ton. Wheels add more: aluminum wheels are lighter than steel. Wide-base single tires replace two duals with one wider tire and can save weight. Our guide to how much semi truck tires cost covers tire prices.
Engine weight
Heavy duty diesel engines are among the heaviest single components on a truck, often weighing a few thousand pounds dry. Engine weight differs by maker, displacement and configuration. Check the engine maker's spec sheet for your engine.
Box trucks and straight trucks
Box trucks are rated by gross vehicle weight rating, or GVWR, rather than measured against the tractor-trailer limits. Many 26 ft box trucks are rated at 26,000 pounds GVWR, which means the truck and cargo together must not exceed that figure. Others are rated higher. Find the GVWR on the label on the driver's door frame. That rating also decides whether a CDL is needed.
Weight and wear
Heavier loads put more work on the engine, brakes, tires and suspension. Trucks that run at or near gross weight usually go through brakes and tires faster, and burn more fuel per mile. That is worth pricing into your rate. The maintenance reserve calculator helps set aside money per mile for the wear, and our guide to semi truck maintenance cost covers what the common items cost.
Weight and fuel economy
Weight affects fuel economy more than most other factors. A truck pulling close to the gross limit burns noticeably more fuel per mile than the same truck running light, especially on hills and in stop-and-go traffic. When you compare loads, a heavy load that pays the same as a light one usually costs more to haul. Compare your own loaded and empty fuel economy with the semi truck MPG calculator, and factor the difference into the rates you accept.
How to weigh your truck
Certified truck scales are found at many truck stops and some fuel stations. Weigh the truck with your usual fuel load and equipment to get your real empty weight, then keep the ticket. When loaded, a scale ticket shows the weight on each axle group, so you can slide the tandem or fifth wheel to stay legal on each axle before you head out.
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