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Michigan frost laws: seasonal weight restrictions for trucks

Helm PartnersUpdated Nov 2, 2026Sources checked Nov 2, 2026
Short answer

Michigan law cuts legal axle loads during the spring thaw: by 25% on concrete pavements and 35% on other roads (MCL 257.722(8)). MDOT sets the dates for state highways each year from frost-depth readings, and county road commissions set their own. On MDOT's green and gold all-season routes, legal axle weights are not reduced.

In this guide
  • What the law says
  • How MDOT sets the dates
  • All-season and seasonal routes
  • County and city roads
  • Exemptions, including milk and farm loads
  • Fines and unloading
  • How a fleet plans for it
  • FAQ

Every spring, thawing ground under Michigan roads gets soft, and the state cuts legal axle loads to protect the pavement. Here is how the restrictions work, where they apply, who is exempt, and how a growing fleet plans around them.

What the law says

  • During March, April and May, maximum axle loads drop 25% on concrete or concrete-base pavements and 35% on all other roads (MCL 257.722(8)).
  • Wheel loads are capped at 525 pounds per inch of tire width on concrete and 450 on other roads while the restrictions are in effect.
  • MDOT and each local road agency must post the dates and the roads covered on their websites.
  • MDOT, or a local authority for its own roads, can lift the restrictions or impose them at other times when road conditions call for it (257.722(10)).

How MDOT sets the dates

MDOT says it decides from frost-depth data, road conditions and weather forecasts, and keeps restrictions in place until roadbeds are stable again. They start in the south and lift from south to north.

  • 2026 start. 6 p.m. Tuesday, Feb 17, from the Indiana and Ohio borders north to the US-10 line (MDOT, Feb 12, 2026).
  • 2026 end. MDOT lifted the remaining restrictions on all state trunklines at 7 a.m. Friday, May 15 (MDOT, May 13, 2026).
  • Updates. MDOT posts each change as a numbered spring weight restriction bulletin, takes calls at 800-787-8960, and offers email alerts.

All-season and seasonal routes

  • All-season routes, green and gold on the MDOT Truck Operators Map: no reduction in legal axle weight.
  • Seasonal routes, solid or dashed red on the map: a posted 25% cut for rigid (concrete) pavement and 35% for flexible (asphalt) pavement, and a 35 mph limit for some vehicles.
  • Permits. In the restricted area, extended permits are valid for oversize loads only. MDOT does not issue single-trip permits there for overweight loads or loads over 14 feet wide, 11 axles or 150 feet long. More on permits: Michigan oversize and overweight permits.

County and city roads

County road commissions and city public works departments set their own seasonal restrictions. MDOT says they usually, but not always, match the state highway dates, and signs mark the restricted routes. The County Road Association of Michigan map lists each county's status, its all-season and restricted road lists, and links for county permits.

Exemptions, including milk and farm loads

  • Farm loads. Hauling agricultural commodities to or from a farm is exempt on county roads if the person picking up or delivering notifies the county road commission at least 48 hours ahead. The commission issues a permit with the route, time window and any speed limit (MCL 257.722(5)).
  • Milk. MDOT and county road commissions may grant exemptions for milk on specified routes when asked in writing, and must answer within 30 days. A denial must give the reason and alternate routes, and can be appealed (257.722(9)). For milk haulers: milk tanker hauling in Michigan.
  • Others. Public utility vehicles on local roads (with conditions in 257.722(6)), school buses, and propane delivery to a home with the tank no more than half full at 35 mph or less.

Fines and unloading

  • An officer, or an authorized MDOT or county road commission agent, can stop a truck to weigh it and require the load to be shifted or removed until it is legal (MCL 257.724).
  • Freight unloaded that way is the owner's or operator's responsibility, at their risk.
  • The owner, the lessee of an owner-operator's truck, or anyone who causes or allows the overweight load is responsible for a civil fine per pound of excess load: 3 cents a pound at the low end, up to 20 cents a pound when the excess is over 10,000 pounds (257.724(3)).

How a fleet plans for it

  1. Map each regular customer and yard against the all-season routes before February.
  2. Check the county map for the first and last miles, which are often county roads.
  3. Sign up for MDOT's email alerts and assign one person to watch the bulletins.
  4. Plan lighter loads or extra trips on seasonal routes, and tell shippers early.
  5. For milk or farm loads, get the written exemption or county permit before the season and keep it in the cab.
  6. If freight ever has to come off at a scale, know who picks it up. Ask whoever handles your insurance how your cargo coverage treats it.

Hauling heavy freight in Michigan: flatbed trucking in Michigan and dry van trucking in Michigan. Growing past a few trucks: insurance for fleets of 3 to 20 trucks.

FAQ

When do Michigan frost laws start and end?

The law names March, April and May, but MDOT can impose or lift restrictions at other times when road conditions call for it (MCL 257.722(10)). In 2026, MDOT started them at 6 p.m. Feb 17 in southern Michigan and lifted the last ones at 7 a.m. May 15.

How much weight do I lose under Michigan seasonal restrictions?

On seasonal routes, maximum axle loads drop 25% on concrete or concrete-base pavement and 35% on other roads. Wheel loads are capped at 525 pounds per inch of tire width on concrete and 450 on other roads (MCL 257.722(8)).

Do frost laws apply on all-season routes?

Not on MDOT's all-season routes, shown in green and gold on the Truck Operators Map. There is no reduction in legal axle weight there. Seasonal routes are shown in solid or dashed red, and some vehicles there also have a 35 mph limit.

Do county roads follow MDOT's dates?

Not always. County road commissions and city public works departments set their own restrictions, which MDOT says usually but not always match state highways. The County Road Association of Michigan map shows the status by county.

Are milk and farm loads exempt?

Farm loads to or from a farm are exempt on county roads with 48 hours' notice to the county road commission and a permit (MCL 257.722(5)). For milk, MDOT and county road commissions may grant route exemptions on written request and must answer within 30 days (257.722(9)).

What is the fine for running overweight during frost laws?

Overweight is a civil infraction with a fine per pound of excess load, from 3 cents a pound at the low end to 20 cents a pound when the excess is over 10,000 pounds (MCL 257.724(3)). An officer can also require the load to be shifted or removed before the truck moves.

This guide is general information, not legal advice. Restrictions change each season, so check MDOT and your county road commission before you dispatch.

Sources

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