Introduction to the Steer Axle Weight
When a truck or heavy vehicle travels on public roadways, it makes physical contact with the bituminous mat under. This contact is what allows the truck to have traction and control for safely driving down the road. However, this also creates a situation where the weight of the truck can cause damage to the roadway.
This is why the state and federally regulated vehicle weights. Specifically, there are laws in place that limit the amount of weight that a truck can have across its axle system.
There are two components to the weight of a truck:
The total gross weight, as you might imagine, cannot exceed the federal limit of 80,000 lbs. That limit, however, is the sum of the total it is of all 5 axles. There are different weight limits for each axle. To keep the truck balanced and to prevent roadway contact, there are strict regulations on steer axle weight.
What is Steer Axle Weight?
Most trucks have a front wheel-drive and four-wheel drive option. The purpose of the front wheels is to allow steering, thus the name "steering wheels" or "steer axle." Steer axle weight is the weight imposed by the tires of the steer axle. This weight might seem inconsequential but is one aspect of the weight distribution that determines whether or not your truck is pulling evenly or skewing weight to only one side.
It is the steering axle weight that determines how well your truck will perform when navigating tight corners. When a driver begins to turn at high speeds and the weight is not evenly distributed , it can cause the truck to tip. For this reason, steer axle weights are strictly controlled.
Steer axle loads are controlled using the concept of "steering rearward." This means that the amount of weight on the steer axle should be larger than the loads on the rear wheels by a certain percentage.
The Importance of Properly Distributing Steer Axle Weight
Properly distributing the steer axle weight is an important facet of transportation. If the steer axle weight is improper, it can lead to accidents and cause irreparable damage to state infrastructure. The weight is so important that any 10% increase in the steer axle weight can result in 20 times the amount of damage to the roadway.
Perhaps the largest issue related to steering axle load is when a truck is fully loaded, the steering axle is frequently overloaded. Most truck manufacturers place the front axle further to the rear of the cab, making it easy to overload. When this happens, the front suspension is unable to absorb the shock from the road, which causes the tires to easily become damaged.
Due to the significance of correct steering axle weight, violations can result in hefty fines. Further, they can even result in your truck being placed out of service for several hours.
Federal Regulations on Steer Axle Weight
In the United States, the federal government regulates the maximum weights allowed on the various axles of commercial motor vehicles. These regulations are contained in Title 49, Chapter III of the Code of Federal Regulations (CFR), which is known as the Federal Motor Carrier Safety Regulations (FMCSR). The regulations at 49 CFR § 658 provide that the maximum allow axle weights be determined using the Federal Bridge Formula (bridge formula), which in turn is defined at 49 CFR § 658.5 and § 658.11. The applicable formula for the subject regulations provides: Where: first = the distance in feet between the extremes of any group of two or more consecutive axles, the center of the first such axle group being no less than one foot nor more than 50 feet from the beginning of the group. b = 36 N = Number of axles in the vehicle/trailer combination LN = Overall length in feet of the vehicle/trailer combination minus four feet for each front and/or rear overhang of more than four feet. The maximum weight permitted under the formula for a single axle (first = 1) at 12,000 lbs.; for a tandem (first = 2) at 34,000 lbs.; for a tridem (first = 3) at 42,000 lbs.; and for a four-axle group (first = 4) at 50,000 lbs. See 49 CFR § 658.5. In addition to the limits imposed by the bridge formula, the FMCSRs require that no single axel shall exceed a gross weight of 20,500 lbs., with no tandem exceeding 34,000 lbs., no tridem exceeding 42,000 lbs., and no four-axle group exceeding 54,000 lbs. While a violation of the regulations shown above can result in civil penalties issued by the DOT, the individual states have the authority to enforce additional restrictions on weight, and also issues civil citations. See 49 CFR § 658.15.
State-Specific Steer Axle Weight Limits
State regulations can vary from federal law when it comes to the legal limits placed on your truck’s steer axle weight. This is largely because truck weight laws are derived not only from federal law and regulations enacted by the Federal Motor Carrier Safety Administration (FMCSA), but also from the size and weight regulations of state departments of transportation, or their equivalent state agency. Simply put, each state has the power to impose its own truck and freight transportation regulations as long as they do not conflict with federal law.
Some states have implemented their own limits on steer axle weight. Portions of Massachusetts, New York and Florida, for example, have restricted steer axle weight to 19,000-pounds or less. In Pennsylvania, some bridges have weaker enforcement tolerances, which can mean that trucks that would legally be considered out of compliance by FMCSA may pass muster with Pennsylvania’s stricter bridge requirements. The legal steer axle weight limit in most states is 20,000-pounds or more, so any state-imposed steer axle restriction of 19,000-pounds or less means that those trucks cease to be road legal at a much lower weight than would be the case under federal law.
Impact of Exceeding the Legal Weight Limit
The consequences of exceeding legal weight limits are not limited to a fine. Commercial vehicle operators are also subject to road use tax, distance taxes, and mileage taxes such as Kentucky’s International Fuel Tax Agreement (IFTA) and International Registration Plan (IRP) requirements. When the overweight load is detected by a weigh station or an officer, the carrier can be fined for the entire load being overweight. But, the penalties become even more serious in the event of an accident . Both civil and criminal liability issues may arise, including vicarious liability claims against the carrier and its principals. In the event that a company officer knew or should have known of the overweight condition, the officer and the company might also be subject to criminal charges. The decision to proceed down the highway with an overweight load is not one that can be taken lightly. Even if operationally expedient, the risk associated with overweight loads may expose a carrier to significant civil and criminal liability.
Recommended Practices for Legal Steer Axle Weight
Achieving legal steer axle weight requires a combination of proper loading techniques, regular monitoring, and effective use of technology. Here are key strategies and tips for truck operators: Distributing Weight Along the Truck’s Axles: The mechanism that maintains the balance for the distribution of the weight of the load on the trailer, is the axles. Having the right number of axles is important. The heavier cargo you are carrying the more axles you will need which also means you have a longer truck. You can also shift the weight of the load in accordance with the number of axles you have and the weight capacity for each axle. Check your truck’s manual to find the specifications. Tires: the weight distribution will also depend on the type of tires on your truck and trailer. Regularly check the condition of your tires to ensure they are properly inflated and free of damage. New Technology: another way to avoid steer axle weight violations is to make use of new technologies available on the market. On-board weight systems help truck drivers to actively monitor their load by providing real-time information on how the cargo is distributed across the truck’s axles. Furthermore, GPS technology and route-planning software will also help drivers to understand any limitations on the distribution of their cargo. Anticipating Weight Distribution on Individual Loads: Not all loads are created equal and it is important to understand how a specific load will affect the distribution of the truck’s weight. As a rule, you should keep heavy items low and put lighter items on top, but by complying with this rule alone it may not be enough. Every load has a unique profile and as the cargo shifts during the driving, some of the weight may shift in the opposing direction causing the steer axle to exceed its capacity. Anticipate how your load will distribute on the road and move the heaviest items to the front when you know that you will be on uneven ground or rough roads.
Technological Solutions for Managing Weight
Traditionally, legal steer axle weight management has relied on periodic weigh-ins and load adjustments, which is not the most efficient approach. Technologies, however, are now available to help operations plan loads with greater accuracy and ensure compliance more consistently. For example, onboard scales are an excellent way to monitor steer axle weights in real time. They can be installed easily and are very accurate. In particular, in-motion scales, which require no driver intervention, continuously monitor weight as a vehicle passes over a scale pad on the road. Because the system measures weights in real-time, drivers do not have to stop and weigh-in , and can immediately make adjustments if required (such as moving freight or fuel to other axles). These scales are also cost-effective when weighing larger fleets because the scales can accommodate multiple vehicles and vehicles weighing multiple trailers at the same time. In some cases, in-motion scales can be permanently installed on the highway. Telematics systems, meanwhile, can be excellent tools for planning loads in a manner that is compliant with federal and state weight regulations. Embedded in most commercial fleet vehicles, telematics devices transmit multiple vehicle metrics to an operations manager, including vehicle weight. These systems can automatically analyze weight data from multiple vehicles and, in some cases, allow managers to adjust freight loads remotely.