The Skinny On Truck Weights & Measures

More Americans than ever before are becoming overweight. The latest numbers say that 63.1% of adults in the U.S. were either overweight or obese in 2009. And, if you’re in the trucking business, your truck might be overweight, too. Motor carriers hear a lot about vehicle weight and it can be very confusing. So, let’s look at some of the specific truck weights and then discuss the broader issue of CMV size and weight.

Gross Vehicle Weight (GVW). This is the total weight of the loaded vehicle. This includes the vehicle itself and the cargo that is loaded on the vehicle.

Gross Combination Weight (GCW). This is specified by the manufacturer as the maximum loaded weight of a truck/tractor plus the trailer or semi-trailer designed for use with the truck/tractor.

Gross Vehicle Weight Rating (GVWR). This is the rating that is calculated by the manufacturer as the amount of weight that the vehicle will be when the vehicle itself is weighed filled with fuel and loaded according to the manufacturer’s specification.

Gross Combination Weight Rating (GCWR). This is the maximum allowable combined mass of a towing road vehicle, passengers and cargo in the tow vehicle, plus the mass of the trailer and cargo in the trailer. This rating is set by the manufacturer.

Safety Compliance Weight. The Federal Motor Carrier Safety Regulations (FMCSRs) have two definitions of a Commercial Motor Vehicle (CMV) for interstate carriers; each definition applies to specific safety regulations. Sec. 390.5 defines the weight of a CMV as 10,001 lbs. or more GVW/GCW or GVWR/GCWR. In this situation, the FMCSA may use either the GVW or the GVWR (whichever is highest). If the actual GVW of your vehicle is 9,150 lbs. but it has a manufacturers’ GVWR of 10,500 lbs., it is a CMV subject to the rules. The definition in Parts 382 and 383 says a CMV is 26,001 or more lbs. GCWR or GVWR. In this case, only the manufacturers’ weight rating matters. The actual gross vehicle weight is not a factor in determining compliance. When a state adopts the FMCSRs for their intrastate carriers, a different weight threshold may be adopted for intrastate compliance.

Registration Weight. The registered weight of a vehicle is not related to any compliance with the FMCSRs. A vehicle must be registered for the actual gross weight or combined gross weight. This means the empty weight of the vehicle plus the empty weight of any towed vehicle, plus the weight of the heaviest load to be carried. Generally, vehicles should not be registered for a weight higher than the weight rating; most states will not allow registration exceeding the weight rating. If the vehicle travels on the highways at a weight higher than the registered weight shown on the registration, a citation may be issued for overweight on vehicle registration. If your vehicle has a GVWR of 13,000 lbs. but is registered for 9,999 lbs., it may be registered for the correct weight, but will still be subject to most of the FMCSRs because the GVWR is over 10,001 lbs. Any vehicle operating interstate with a GVW or GCW or registered weight of 26,000 lbs. or more, or having three axles at any weight, is subject to the International Registration Plan (IRP) for apportioned registration and the International Fuel Tax Agreement (IFTA) for payment of fuel use taxes. These base state agreements do not use the vehicle weight rating when determining compliance.

Highway Weight. This is the legal weight related to highway size and weight limits. When operating on the interstate system, the maximum permissible weight is 20,000 lbs. on a single axle, 34,000 lbs. on a tandem axle, and 80,000 lbs. max gross weight. The “Bridge Formula” allows motor vehicles to be loaded to the maximum weight only if each group of axles on the vehicle and their spacing also satisfy the requirements of the formula. States must use these limits for their designated or national network highways. While the majority of the states use the federal bridge formula for all roads in their state, some do have a separate state formula for other state or county roads.

Now that all of us understand (I hope) the basic vehicle size and weight limits, just what types of vehicles are required to stop at weigh stations? This question can often be hard to answer because it is a state-by-state requirement. Some states require “all trucks” to stop, regardless of weight, while other states will require only those vehicles above a certain weight to stop. Sometimes, when states establish weight minimums, they will base the requirement on the GVW, GCW, GVWR or registered GVW. Signs will be posted prior to the station advising who must stop. If the requirements apply to you, then you must stop. If you are unsure, contact the state’s department of transportation or commercial vehicle enforcement office. Or, better yet, just stop at the weigh station.

Another question that I have run across is, why do states limit the distance from the kingpin to the rear axle or center of rear axle group on semi-trailers over 48 feet? These limits are in place to shorten a combination’s wheelbase and thereby tighten the turning radius of the vehicle. Almost half of the states have established kingpin to rear axle distances for trailers over 48 feet (some apply only to 53-foot trailers). Usually, the distance limits range anywhere from 38 feet to 43 feet, depending on the state and type of trailer. The following states have adopted a kingpin to rear axle limit: AL, CA, CT, FL, IL, IN, ME, MD, MI, MN, NH, NJ, NY, NC, PA, RI, SC, VT, VA, WV and WI.

Do you know what the federal vehicle height limit is? The federal regulations do not establish a vehicle height limit. States are responsible for establishing such limits, and the limits usually range anywhere from 13’6” up to 14’6”. All states will allow at least 13’6” on their interstate highways. On state and local highways, most states will allow 13’6” but be aware that the limits may be lower. Further, the FMCSRs do not contain the size and weight regulations. The regulations actually fall under the Federal Highway Administration (FHWA) regulations found at 23 CFR Part 658.