Weights and Dimensions

This training is applicable to:


Weights and Dimensions

Section 1


Weights and Dimensions


In part four we will review:

  • What factors influence a vehicle’s weight allowance
  • What are legal load limit, safety measures, and related exemptions that apply to weights and dimensions
  • What factors determine the max allowable length for a vehicle and load
  • How do weights and dimensions pertain to highways versus local roadways
  • What are road bans and how do they impact driving operations
  • What are over-dimensional permits and how are they used

Note: this training is based on Alberta’s Commercial Vehicle Dimension, and Weight Regulation AR315/2002. 

Why are Vehicle Weights and Dimensions Important?

The Alberta Traffic Safety Act includes weights and dimensions as a means to ensure public safety and protect Alberta’s roads. Each province and territory has its own set of laws that dictate the acceptable maximum weight and dimension of a vehicle on a road. 


Section 2

Allowable weight

Weights and Dimensions


In this section we will review:

  • What is allowable weight
  • How allowable weight is determined
    • Tires
    • Axles
    • Axle Groups
    • Full Trailers
    • Additional Configurations
  • Tare
  • Gross Vehicle Weight
  • Gross Combination Weight
  • Registered Weight

What is Allowable Weight?

Refers to both the laws that restrict how heavy a vehicle and load can be while travelling on various roadways, as well as the maximum weight of a vehicle, its load, cargo, components, etc.

Factors that can influence the allowable weight limit of a vehicle include:  

  • The type of the vehicle
  • The number of axles
  • The axle groupings
  • The distance between each axle group
  • The manufacturers rating of the vehicle
  • The size of the tires
  • The configuration of the vehicle

Carriers are responsible for ensuring their vehicles are in compliance with the weight restrictions that may apply. 

How is Allowable Weight Calculated?

An online calculator is available through AB Transportation’s website:


This calculator is meant to assist with interpreting parts of the legislation, not substituting them. Carriers still need to ensure that they are adhering to the regulations.


Maximum weights of tires are calculated by:

  • The capacity and width of the tire
  • Multiplying 10 kg by the cross section dimension on the tire (mm)
  • As per the legislation the gross allowable weight on a tire cannot exceed 3650 kg

Regardless of the tires used, you are only allowed the maximum weight in which the axle is rated for. Larger tires may mean you can add more weight but this is not recommended.

Reputable tire shops will not typically sell tires that are rated for more than the axle can handle as the axle wouldn’t be strong enough to handle the stress that the larger tire puts on it.


Gross Axle Weight Rating (GAWR) is the maximum allowable weight that can be put on each axle.

There are two types of axles:

  • Steering axles
  • Carrying axles

Truck Tractors – Steering Axle

As set out by the legislation, a tractor that is coupled with a fifth wheel trailer has the maximum allowable weight limit of 5500 kg (12000 lbs) on the steering axle, regardless of whether or not you use larger tires.





Trucks/Body Jobs – Steering Axle

Trucks/Body Jobs are any motor vehicle designed for and intended to transport goods or carrying loads. This includes vehicles such as gravel trucks, bed trucks, winch trucks, pickers, buses, etc.

Trucks have a maximum allowable weight up to 7300 kg (16000 lbs) on the steering axle.

What is the maximum gross axle weight rating for the steering axle of a body job gravel truck?

  • 5500 kg
  • 7300 kg
  • 10000 kg

Carrying Axles

The maximum allowable weight of carrying axles is based on the size and number of tires as well as the GAWR of the axle.

The maximum allowable weight for carrying axles is based on whichever of the following has the lowest rating:

  • Tire Capacity
  • Axle rating
  • The max rating for the axle group*

*axle group refers to the number of axles positioned together in the same area of a vehicle 

Axle Groups

We will review the following axle groups:

  • Single
  • Tandem
  • Tridem

Important terms:

  • Axle Spacing - the distance between two axles or axle groups (the steering axle and the next adjacent axle from the axle group) which is calculated from the centre of each axle. 
  • Axle Spread - the distance between the outside axles in an axle group which is calculated from the centre of each axle

Single Axle Group

Is a vehicle with: 

  • An individual axle or

  • A combination of 2 axles with an axle spread less than 1m

Allowable weight on a single axle cannot exceed 9100 kg

Tandem Axle Group

2 consecutive axles in a group with an axle spread between 1.2 m and 1.85 m

Tridem Axle Group

3 consecutive axles in the group with an axle spread between 2.4m and 3.7m excluding lift axles in the down position or a single steer axle

Note: On local roads, without a permit, the allowable weight on a tridem axle group cannot exceed 17000 kg

Twin Steers and Tri-drives

Twin Steers are vehicles with two steering axles.

Tri-Drives are vehicles with three carrying axles.


Note: Vehicles outside the normal configurations such as these require a permit to operate.

Tare Weight

Tare weight refers to the weight of the vehicle and its components when it is not loaded.


You can determine how much weight can be carried by a truck by subtracting its tare weight from its GVW. This amount is often referred to as the payload or load weight. 

Gross Vehicle Weight (GVW)

Regardless of the allowable weight a vehicle is capable of hauling the weight of the vehicle must not exceed the manufacturer’s maximum weight limit.

GVW includes:

  • The weight of the vehicle,
  • The weight of the vehicle’s components,
  • The weight of the load, passengers, driver, etc.

To find a vehicle's GVW, check the owners manual or the driver's side door post.

Gross Combination Weight Rating (GCWR)

The GCW is the combined GVW of the vehicle and trailer. Which includes:

  • The weight of the vehicle and trailer,
  • The weight of the vehicle and trailer components,
  • The weight of the load, passengers, driver, etc.


Registered Weight

Registered weight is specified when a vehicle is registered:

  • This can be to a maximum of 63500 kg.
  • It is important that the registered weight of a configuration does not exceed the amounts previously discussed.
  • When driving, it is also important that you do not exceed the weight the vehicle is registered for.

Example: A tandem tractor and tri-axle trailer is registered for 46500 kg. You decide to haul a loaded full trailer which changes the allowable weight to 55300 kg. This means if you loaded based on the allowable weight of the vehicle and trailer you would be in violation of your registered allowable weight. This could result in a hefty fine and a hit to the organization’s carrier profile.  

So why don’t we register all our vehicles for the max of 63500 kg?

Registration fee is based on weight, therefore registering our entire fleet for the maximum amount, when the vehicle would NEVER haul it would cost significantly more then registering it for the appropriate weight.

The GCW (Gross Combination Weight) is typically the registered gross weight of the vehicle and trailer combined, however in Alberta it is possible to register them separately.  This makes it possible for different trucks to haul different trailers. 

What does it all mean?

In order to be legal, the weight must not exceed:

  • The GVW of the truck
  • The GCW of the truck and trailer
  • The combined GAWR of both the steering and carrying axles
  • The allowable weight rating of each axle group
  • The allowable weight rating for the tires on the vehicle
  • The allowable weight rating for the roads you are travelling on, and
  • The registered allowable weight

Failure to adhere to these restrictions could result in damage to the equipment, costly fines, and hits to the carrier’s profile.

A tandem gravel truck would have:

  • A max steering axle weight of 7300 kg
  • A max tandem axle carrying weight of 17000 kg
  • A GVW of 24300 kg 

This would mean that  even though you are allowed to have up to 24300 kg total weight on the truck, if you exceed 17000 kg on the carrying axles you would still be overweight. 

Section 3

Width and Height

Weights and Dimensions


In this section we will review:

  • Load width
  • Vehicle width
  • Load height
  • Safety precautions
  • Exemptions

Allowable Load Width

The standard legal load width is 2.6 m (8’6”)

  • Any load that is wider than the standard requires an over dimensional permit.
  • The outside rear view mirrors are not included in the width of a vehicle unless the mirror sticks out greater than 20 cm beyond the widest part of the vehicle/load.

  • Cargo securement devices are not included in determining the width unless the device sticks out 10 cm past the widest part of the vehicle or load.


Allowable Load Height

The standard legal load height is 4.15 m (13’6” or 13.5 ft)

  • Any load that is higher than the standard requires an over dimensional permit.


Depending on the width of the load you may be required to use flags, signs, or other warning devices to alert others to the width of the load.

As per AR315/2002 you are required to alert to over width loads.

  • Dimensional signs must be affixed in a way on the front of the vehicle in a way that the sign is visible to oncoming traffic as well as at the extreme rear of the vehicle or load (whichever is further) so it is clearly visible to approaching traffic. Signs must be clean, in good condition, and visible.
  • Flashing lights/lamps refer to stationary or rotating lights that can flash, strobe, or turn and must have an indicator light inside the cab to alert to when it is on. 

If you are hauling any cargo that exceeds 5 m in height or 5.49 m wide refer to the legislation for additional precautions. 

It is important that all conditions mentioned are complied with when needed unless there is a permit or exemption in place. (i.e. farm equipment with the appropriate warning markings).

Although you can be ticketed for hauling a wide load without the necessary precautions it is also ticketable to use these precautions when they are not needed – as such use them appropriately and cover or remove them when they are not needed. 


The following vehicles are exempt from the maximum weight (9) and maximum dimensions (4) regulations:

  • Vehicles required to transport materials needed for the emergency maintenance of a highway
  • A vehicle transporting equipment to a forest fire, flood, train derailment, pipeline spill, or other emergency.
  • Farm equipment and materials (see legislation for further detail)
  • Road construction and maintenance equipment are exempt from width restrictions when driven or hauled during daylight hours and have the appropriate warning markers displayed

Section 4


Weights and Dimensions


In this section we will review:

  • Load Length
  • Vehicle Length

Allowable Load Length

Maximum allowable load length is 25 m (82 ft)

  • The design and type of vehicle will affect the allowable length.