Michigan Truck Weight Limits

How much a truck can weigh in Michigan

Michigan is the outlier. On designated routes an 11-axle truck can gross up to 164,000 lb, more than double the federal 80,000 (MCL 257.722). Michigan regulates by axle, not gross, so its single-axle limit is actually lower at 18,000 lb, and the big weights come from spreading load across 11 axles at about 13,000 lb each. Fines run 3 cents a pound at 1,001-2,000 over and climb to 20 cents a pound past 10,000 over (MCL 257.724).

Axles, off-Interstate, and permits

• Off the Interstate: Up to 164,000 lb on an 11-axle rig on designated state trunklines; 80,000 lb for a standard 5-axle truck (MCL 257.722)
• Single axle: 18,000 lb, below the federal 20,000
• Tandem axle: 34,000 lb; the heavy trains carry load at about 13,000 lb per individual axle spread across 11 axles
• With a permit: 164,000 lb on an 11-axle combination, statutory and requiring no overweight permit on designated trunklines and grandfathered interstates (MCL 257.722).
• Michigan's 164,000 lb is grandfathered onto its interstates as well as state trunklines. It comes from axle count, not from higher per-axle limits; the standard 5-axle semi is still 80,000 lb.

Posted bridge and road limits

Michigan's spring weight restrictions are the ones that bite: from roughly March to May, allowable axle loads on posted routes drop sharply (commonly cited near a 25 percent cut) while roads thaw. Bridges carry 'WEIGHT LIMIT X TONS' postings in 2,000-lb short tons, and the posted number beats your legal gross. Cross a posted bridge over its rating and it's a separate violation with liability for structural damage on top.

What running heavy costs

Civil fine by cents-per-pound of excess under MCL 257.724: 3 cents a pound at 1,001-2,000 over, 6 cents at 2,001-3,000, 9 cents at 3,001-4,000, 12 cents at 4,001-5,000, 15 cents at 5,001-10,000, and 20 cents a pound past 10,000 over. Example: 8,000 lb over runs about $1,200.

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