New Hampshire Truck Weight Limits

How much a truck can weigh in New Hampshire

New Hampshire stops at 80,000 pounds on the Interstate, the plain federal limit (RSA 266:18). Off the Interstate a 6-axle rig can run to 99,000 pounds by permit, and the state gives a 5% enforcement tolerance on non-Interstate roads that it does not give on the Interstate. Single axle goes to 22,400 and tandem to 36,000 off the Interstate (RSA 266:18-a). A first overweight ticket is $100 or 2 cents a pound over, whichever is greater; repeat offenders past 30,000 pounds over hit 4 cents a pound (RSA 266:25).

Axles, off-Interstate, and permits

• Off the Interstate: 80,000 lb; 99,000 lb for 6-axle combinations on approved non-Interstate routes
• Single axle: 22,400 lb off the Interstate; 20,000 lb on the Interstate
• Tandem axle: 36,000 lb off the Interstate; 34,000 lb on the Interstate
• With a permit: 99,000 lb / 6-axle combination on approved non-Interstate routes by permit; special/superload permits higher case-by-case.
• New Hampshire is not a federally grandfathered heavy-Interstate state; the Interstate max is the federal 80,000. The 22,400-lb single / 36,000-lb tandem figures apply off the Interstate to configurations at or under 73,280 lb; heavier combos revert to 20,000/34,000. The 5% tolerance does not apply on the Interstate.

Posted bridge and road limits

New Hampshire posts bridges and local roads 'WEIGHT LIMIT X TONS' in short tons (6 TONS = 12,000 lb), and Class V/VI roads get reduced 'frost law' postings during spring thaw. The posted number overrides the legal max, so you detour rather than cross a bridge posted below your weight. Crossing a posted bridge or road over its limit is a separate violation, and you can be held responsible for damage to the structure.

What running heavy costs

RSA 266:25. 1st offense $100 or $0.02 per lb over the prescribed weight, whichever is greater; 2nd offense $250 or $0.02 per lb. 3rd and subsequent offense of the same vehicle: $250 or $0.02 per lb up to 15,000 lb over; $0.03 per lb when 15,000-30,000 lb over; $0.04 per lb when more than 30,000 lb over. Off-Interstate roads carry a 5% enforcement tolerance; the Interstate gets none.

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