Tractor Trailer Axle Weights

Understanding axle weights is extremely important in the heavy haul industry. Knowing the tractor trailer axle weights is vital to ensure a shipment is hauled legally. The first thing to point out is there are several different types of axle configurations. Secondly, states vary about what the rules are for these different axle configurations. So lets break it down:

Axle Configurations

Steer

– The first axle and in fact steers the tractor.

Single

– A single axle is generally seen in a smaller tractor trailer setup or on a spread axle trailer or as a booster.

Tandem

– This is the most common tractor trailer axle configuration setup. Generally you have a drive tandem and a trailer tandem.

Tri-Axle

– Three axles arranged together and are found on drives, trailers, or both.

Quad-Axle

– Four axles arranged together and found on trailers.

State Regulations

As mentioned, states range when it comes to axle limits. So review our Permits and Escorts Page for a list of axle weight limits by state.

Max Legal Limits

– The max weight allowed on any axle configuration without requiring a permit. Typically 34,000 lbs on a tandem.

Max Permit Limit

– This is the max weight allowed on any axle configuration with a permit. Averages around 44,000 lbs on a tandem.

Gross Weight Limit

The max gross weight of a shipment with a tractor trailer combination is 80,000 lbs. This is only a part of the story. States also have as mentioned axle weight limits. So the image below shows a typical flatbed setup with max legal weight limits listed. If you add all those weights up you get 80,000 lbs.

However, it’s very difficult to get a trailer loaded so your axle weights would equal 80,000 lbs without going over on a set of axles. For example you might have 80,000 lbs total on your trailer like the image below, but you are over the legal limit on the drive tandem.

Not to over simplify this process, but typically an item can be adjusted in the case above you might move the product toward the back of the flatbed so the weight is evenly distributed on both the drive and trailer tandem axles.

Other Important Factors

Frost Laws effect axle weight limits
Moving the product forward or backward will distribute weight differently.
Changing the kingpin setting and/or moving the trailer axle group forward or backward.
Axle spacing within an axle group has a lot to do with what is allowed by states, so check with the states directly.

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My name is Travis Smith and I've been working in the trucking business since 1994 and with Heavy Haul Trucking since 2001. Our office knows about oversize, heavy and specialty loads and how to get your load exactly where you need it, safely and on time.

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