When you are loading a commercial semi-truck for delivery, there are a variety of factors to consider. You must pay attention to the fragility of objects, their weight, the shape of containers, the order in which they are to be unloaded, how easily they can be unloaded, how they are balanced within the trailer, etc. Optimizing your loading strategy can significantly increase your delivery efficiency.
On top of business improvements, you must also load your truck according to state and federal truck axle weight limits. Failure to comply with these regulations can result in a fine that hurts your company more than it saves to try and ignore them. That’s why Syntelic has created a Load Planning software to automatically develop a load plan with these restrictions in mind.
What Are Axle Weight Limits?
Axle weight limits are legal requirements set on the amount of cargo that can be loaded on the weight-bearing portion of semi-trucks. The axles are the sections that span the truck perpendicular to the direction of travel between corresponding wheels. These sections are sturdier and support more weight than areas that are not reinforced.
Axle weight limits differ based on the state and type of truck in question. As a general rule of thumb, the more axles a truck has, the more weight it will be able to carry. Axle weight limits should not be confused with gross weight limits, which set restrictions on the full weight a truck is allowed to carry.
A tandem axle carries roughly 34,000 lbs. If a semi-truck has two tandem axles, it could carry a gross weight of 68,000 lbs. If the gross weight limit in a specific state is 80,000 lbs., it does not matter how many axles a truck has, they are not able to go over 80,000 lbs of total cargo. Additionally, the weight must be properly distributed to only exert the allowed amount of weight on the given axle. If a semi-truck has two tandem axles that each carry 34,000 lbs., that does not mean they can distribute 68,000 lbs. however they want in the trailer.
Failure to properly distribute weight according to axle limits can lead to dangerous situations. Poorly loaded or overloaded vehicles are more likely to topple or lose control. Loose truck cargo can fall into the roadway or cause a rollover accident. For the safety of truck drivers, other drivers, and the roads they drive on, axle weight limits are strictly enforced.
Why Do Truck Weight Limits Exist?
Infrastructure and roads are a massive expense for the state and local governments in the U.S. Large amounts of money are spent on maintaining roads and repairing damages. Damage to these roads is done by heavy vehicles and trucks. As the weight on an axle increases, the amount of damage it does goes up significantly more.
A five-ton axle will do 625 times more damage to the road surface than a one-ton axle. Truck weight limits exist to lessen these damages and save money. As far as why truck drivers and trucking companies should care, failing to follow these regulations can be dangerous and will result in a fine.
Syntelic Load Planning automatically factors axle weight limits into the loading process. Our software helps you fully utilize your vehicles without pushing weight restrictions. It selects the correct truck and creates a load plan that highlights the factors you want emphasized. Whether your focus is delivery efficiency or axle weight limit accommodation, our product will modify plans to fit your needs.
Who Sets Truck Axle Limits?
Truck weight limits are set by both state and federal regulations. The U.S. Department of Transportation (DoT) Federal Motor Carrier Safety Administration (FMCSA) has created laws that apply to interstate highways and most roadways in the U.S. Under federal limits, there should be no more than 20,000 lbs. on a single axle, 34,000 lbs. on a tandem axle, and 80,000 lbs. gross vehicle weight.
Although DoT weight limits per axle are consistent, some states have laws that allow trucks to carry more than the federal limit on non-interstate highways or other roads. FMCSA axle weight limits and size restrictions are typically used as the standard, as many delivery operations span multiple states and must cross multiple regions.
How Are Axle Weight Limits Decided?
There are a few different factors that truck drivers must be aware of when addressing truck axle weight limits. First and foremost is the manufacturer’s axle rating. You should never try to carry more weight than your equipment is built to carry. Trucks, trailers, and tires will have manufacturer limits that should not be exceeded for any reason. Even if your equipment can handle a certain weight, that does not mean that you will be allowed to transport it as per state regulations.
When it comes to legal limits, there are two restrictions you should be aware of—max legal weight and max permitted weight.
The maximum legal axle weight sets the bar for being able to move without a purchasing permit. The max permitted axle weight is the state’s limit on how much weight you can move even with a purchasing permit. Understanding both of these limits is crucial to running a legal and effective operation.
Beyond the previously mentioned federal regulations, all other limits and restrictions are handled at the state level. If you are looking for an overweight permit or trying to determine the amount of weight you can hold on a truck with tridem, quad, or larger axle groups, you will need to research your specific state limits.
Types of Axles
Truck axles are defined by differing characteristics that often correlate directly with how much weight they can carry. For example, a number of axles spaced closely together in a group can hold more weight than a single axle. At the same time, two single axles spaced far enough apart can hold more weight than a single tandem axle. Whether your truck has steer or drive axles will also change your maximum rating. Many states place a lower limit on steer axles because of the increased control they allow.
The type of truck and how the axles are placed can have a direct impact on the restrictions you must follow.
Steer Axle Weight Limit
A steer axle gives direction control to the vehicle through the driver’s steering wheel. There is typically only a single tire on each side of the first axle, which means it cannot carry much weight. Wider tires could increase the bearable weight, but it would make the steering more difficult. With low-weight cargo, this option offers good control. The maximum weight for steer axle semi-trucks is typically between 12,000 and 15,000 lbs.
Single Axle Trailer Weight Limit
On a single axle trailer, the axle is far enough from other axles to not be considered part of a group. Similar to the steer axle, this is a more lightweight design that holds less weight but handles better and often results in better gas mileage. Federal limits on single-axle transportation equipment are between 20,000 to 25,000 lbs. Anything beyond this weight can damage infrastructure.
Tandem Axle Weight Limit
Tandem axles—also called double axles—are when a trailer has two axles spaced more than 40 inches apart. They must be closer than a specific limit that is set by the state the truck operates in. If multiple axles are less than 40 inches apart, they are considered part of a single axle. Tandem axle limits often fall around 34,000 lbs.
Tridem Axle Weight Limit
Tridem axles involve three axles placed within a state-determined limit of one another. Tridems can often hold more than double the amount of weight that single axle trailers can. As expected, however, the driver loses maneuverability as the number of axles increases.
Quad Axle Weight Limit
Commercial trucks typically do not go higher than four consecutive axles. While groups of five or more can be used for certain loads, it is rare enough that many states do not specify weight limits.
What Are Frost Laws?
In some of the nation’s northern areas, additional precautions must be taken in early spring. As snow begins to melt, the moisture will soften the pavement. This lowers the strength of the road, decreasing the amount of weight it can support. Allowable weights will often be reduced during this time of year.
These are called frost laws and may differ from state to state. Be sure to research the area that you are driving through to avoid the chance of an accident.
Truck Axle Weight Limits By State as of 2020
Information is recorded according to the US Department of Transportation
|State||Single Axle (lbs)||Double Axle (lbs)||Tridem Axle (lbs)||Gross Weight (lbs)|
(Federal Bridge Formula)
|Arizona||20,000||34,000||Per state weight table||80,000|
|D.C.||21,000||37,000||Per district weight table||79,000|
|Idaho||20,000||34,000||Per state weight table||80,000|
|Iowa||20,000||35,000||Per state weight table||80,000|
|Maryland||20,000||34,000||Per state weight table||80,000|
|Massachusetts||18,000||34,000||Per state weight table||80,000|
|Michigan||20,000||34,000||Per state weight table||80,000|
|Mississippi||20,000||34,000||Per state weight table||80,000|
|Missouri||20,000||34,000||Per state weight table||80,000|
|Montana||20,000||34,000||Per state weight table||80,000|
|Nebraska||20,000||34,000||Per state weight table||80,000|
|Nevada||20,000||34,000||Per state weight table||80,000|
|New Hampshire||20,000||34,000||Per state weight table||80,000|
|New Jersey||20,000||34,000||Axle N/A||80,000|
|New Mexico||21,600||34,200||Per state weight table||80,000|
|New York||20,000||34,000||Per FBF||80,000|
|North Carolina||20,000||38,000||Per state weight table||80,000|
|North Dakota||20,000||17,000||Per FBF||80,000|
|Oklahoma||20,000||34,000||Per state weight table||80,000|
|Oregon||20,000||34,000||Per state weight table||80,000|
|Pennsylvania||20,000||34,000||Per state weight table||80,000|
|South Carolina||10,000||35,200||Per state weight table||80,000|
|South Dakota||20,000||34,000||Per FBF||80,000|
|Washington||20,000||Per state weight table||N/A||80,000|
|West Virginia||20,000||34,000||Per FBF||80,000|
|Wisconsin||20,000||34,000||Per state weight table||80,000|
Syntelic Load Planning Can Help You Follow Axle Weight Limits
Manual load planning for multi-level delivery operations can be tedious and difficult. Trying to determine the best way to stack cargo for unloading, stability, and legality isn’t easy for a single person or even a team of people. That’s why Syntelic has developed an automated Load Planning software that concurrently addresses all of these different challenges.
It helps reduce expenses and labor costs by streamlining load planning and the loading process. By working together with our Route Planning and Transportation Analytics products, it can update in real-time to adjust load plans for the most efficient deliveries. Load Planning knows what should be on top based on the route and packs according to state axle limits that a vehicle is routed through.
Our products are designed to make trucking and other transportation operations easier for you. If these strategies sound beneficial, fill out our online contact form to start a conversation with us today.