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Michigan truck weight limits: axle loads, interstates and permits

Helm PartnersUpdated Nov 4, 2026Sources checked Nov 4, 2026

This guide is general information, not advice on any policy.

Short answer

Michigan runs two systems. On interstates the federal limits apply: 80,000 pounds gross, 20,000 on a single axle and 34,000 on a tandem. Off the interstate, Michigan uses axle-load limits instead, so a combination with enough properly spaced axles can legally gross more than 80,000 pounds on designated roads. Spring cuts and permits change the numbers.

In this guide
  • Interstates: the federal limits
  • Off the interstate: Michigan axle loads
  • How Michigan weighs a truck
  • Spring weight cuts
  • Farm and timber loads
  • When you need a permit
  • A fleet checklist
  • FAQ

Michigan is known for heavy trucks with many axles, and for good reason: its weight law works differently from most states once you leave the interstate. Here is how the two systems fit together, from the statute itself.

Interstates: the federal limits

  • On the Interstate System the limit is 80,000 pounds gross, 20,000 pounds on any single axle and 34,000 pounds on a tandem (23 CFR 658.17).
  • Groups of axles must also meet the federal bridge formula. Two consecutive tandems can carry 34,000 pounds each if the first and last axles are at least 36 feet apart.
  • Michigan writes the same limits into its own law for interstates and other highways it designates for 80,000-pound operation, including all enforcement tolerances (MCL 257.722(12)).

Off the interstate: Michigan axle loads

Michigan's "normal loading maximum" limits each axle by how far it sits from the next one (MCL 257.722(1)):

  • 18,000 pounds per axle when axles are 9 feet or more apart.
  • 13,000 pounds per axle when axles are more than 3.5 feet but less than 9 feet apart.
  • 9,000 pounds per axle when axles are less than 3.5 feet apart.

On highways MDOT or a local road agency designates as able to carry heavier loads, a tandem assembly can carry 16,000 pounds per axle if no other axle is within 9 feet (257.722(2) and (3)). A vehicle over 80,000 pounds is held to these axle maximums (257.722(12)). That is why Michigan flatbed, steel, aggregate and some dedicated fleets run combinations with extra lift and trailing axles: the legal gross depends on how many axles carry the load and how they are spaced.

How Michigan weighs a truck

Officers weigh individual axles or groups of axles, and the total on all axles is the gross vehicle weight (257.722(11)). A truck can be under its gross and still be overweight on one axle, so axle spacing and load placement matter as much as the total.

Spring weight cuts

From March through May, axle maximums drop by 25% on concrete or concrete-base pavements and by 35% on other roads where seasonal restrictions are in effect (257.722(8)). Dates, all-season routes and exemptions are covered in Michigan frost laws.

Farm and timber loads

Axle maximums rise by 10% for agricultural commodities or raw timber moving from the place of harvest or farm storage to the first point of delivery. The increase does not change gross weight limits and does not apply on interstates or on roads under seasonal restrictions while they are in effect (257.722(13)).

When you need a permit

A load over the legal limits needs a transport permit. MDOT says it issues permits only for vehicles and loads that cannot reasonably be reduced in size or moved another way. County and city road agencies permit their own roads. Fees, permit types and limits: Michigan oversize and overweight permits.

A fleet checklist

  1. Know which roads on each lane are interstate, designated or seasonal routes.
  2. Record the axle count and spacing for every tractor and trailer combination.
  3. Load to the axle limits, not only the gross. Check axle weights at a certified scale when loads vary.
  4. Keep scale tickets with the trip records.
  5. Check posted spring restrictions from March through May before dispatch.
  6. Get permits before moving anything over the legal limits.

Related: flatbed and steel trucking in Michigan, dry van trucking in Michigan and dedicated contract carriage.

FAQ

What is the legal gross weight for a truck on a Michigan interstate?

80,000 pounds including enforcement tolerances, with no more than 20,000 pounds on a single axle, 34,000 on a tandem, and axle groups within the federal bridge formula (MCL 257.722(12); 23 CFR 658.17).

Why can some Michigan trucks gross more than 80,000 pounds?

Off the interstate, Michigan limits each axle rather than the whole truck. Vehicles over 80,000 pounds must keep every axle within the maximums in MCL 257.722(1) to (3), such as 18,000 pounds for axles 9 feet or more apart, so more axles with the right spacing allow a heavier gross on designated roads.

What are Michigan's axle limits off the interstate?

18,000 pounds per axle when axles are 9 feet or more apart, 13,000 pounds when they are more than 3.5 but less than 9 feet apart, and 9,000 pounds when under 3.5 feet (MCL 257.722(1)). On designated highways a tandem can carry 16,000 pounds per axle if no other axle is within 9 feet.

Do spring frost laws lower these limits?

Yes. From March through May, axle maximums drop by 25% on concrete or concrete-base pavements and 35% on other roads where restrictions are posted (MCL 257.722(8)). MDOT and county road agencies set the actual dates.

When do I need an overweight permit in Michigan?

When a vehicle or load exceeds the legal limits in the Michigan Vehicle Code. MDOT issues transport permits only for loads that cannot reasonably be reduced or moved another way, and local road agencies permit their own roads.

This guide is general information, not advice on any policy. For a specific load or route, check the statute linked below or ask MDOT or the Michigan State Police.

Sources