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: during March, April and May, allowable axle loads on restricted routes drop 25 percent on concrete pavement or a concrete base and 35 percent on all other road types, and wheel load drops to 525 lb per inch of tire width on concrete and 450 lb on everything else (MCL 257.722(8)). If you do not know the route is concrete, plan on the 35 percent cut. 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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