North Carolina Bridge Law: 38,000-Pound Tandems and the 41-Foot Kingpin Rule

North Carolina's statute allows 38,000 lb on a tandem and a 10% tolerance on axle-group limits — but the same section keeps the federal 34,000 / 36-foot rule and the 80,000-lb ceiling, and federal limits still control on the Interstate. A 53-foot trailer must keep the kingpin within 41 feet of the rearmost axle or tandem midpoint.

By Avery Schwartz · Former CDL-A driver, 3 years OTR · Updated 2026-09-15

The numbers at a glance

Limit	NC	Where it comes from
Gross weight	80,000 lb	G.S. 20-118 bridge table
Single axle	20,000 lb	G.S. 20-118(b)(1)
Tandem axle	38,000 lb under state law; 34,000 lb federal on the Interstate	G.S. 20-118(b)(2); 36-ft rule for two tandems at 34,000
KPRA / wheelbase	41 ft, kingpin to rearmost axle or midpoint of a tandem	G.S. 20-115.1; semitrailers over 48 ft on primary routes
Bridge formula applies?	Yes — as a table in G.S. 20-118(b)(3), with a 10% tolerance on axle-group limits	Verify tolerance details with NC SHP

Legal limits change and enforcement varies by road. Confirm anything you're betting a ticket on with NCDOT / NC State Highway Patrol.

How North Carolina applies the bridge law

North Carolina's weight statute, G.S. 20-118, reads more generously than most. Single axles are limited to 20,000 lb, but the tandem-axle limit is 38,000 lb, and subsection (b)(3) sets gross weights by a bridge table with a stated 10% tolerance on the maximum and inner axle-group limits. The 80,000-lb ceiling is the top of the table. The same subsection also carries the federal 36-foot rule — two consecutive tandems may each carry 34,000 without penalty if the first-to-last axle distance is 36 feet or more — which tells you the drafters were thinking about federal Interstate limits too.

Here is the practical problem: federal law limits a tandem to 34,000 lb on the Interstate regardless of state statute, except where a state's higher limit was grandfathered. North Carolina's 38,000 is widely reported and widely used on state routes, but how it interacts with Interstate enforcement, and exactly what the 10% tolerance covers, is something we could not verify to our satisfaction from the statute text. Plan on 34,000 per tandem on I-40, I-85, I-95, and I-77, treat 38,000 as a state-route number, and verify the tolerance with the NC State Highway Patrol before you rely on it.

Trailer geometry is standard eastern: G.S. 20-115.1 allows a 53-foot semitrailer on all primary highway routes when, for a trailer over 48 feet, the distance from the kingpin to the rearmost axle — or to a point midway between the two rear axles if they are a tandem — does not exceed 41 feet. Motorsports trailers get 46 feet.

How to slide your tandems for North Carolina

Set the tandems so the kingpin-to-tandem-midpoint distance is 41 feet or less, then slide for the federal 34,000 figure if your route touches the Interstate. If you scale at a truck stop on a state route and the drives read 35,500, do not assume the 38,000 tandem or the 10% tolerance will carry you onto I-95 — slide it.

Worked example. You scale at the first CAT after the shipper: steer 11,800, drives 35,300, trailer tandems 31,900, gross 79,000. Gross is legal; the drives are 1,300 over. Sliding the tandems forward (toward the cab) moves weight from the drives to the trailer axles. On a trailer with 4-inch hole spacing, a hole is worth roughly 250 lb, so 1,300 lb needs six holes: drives about 33,800, tandems about 33,400. Both groups are under 34,000 with a few hundred pounds of margin, and the gross hasn't changed. Now check the geometry for North Carolina using the row in the table above — and if you'll cross into a stricter state, set for that one instead. The Tandem Slide Calculator does the hole math for your trailer's actual rail spacing and tells you which direction to move.

Common tickets in North Carolina

Based on the statutes above and what drivers commonly report; citation practice varies by officer and county, so treat this as a watch list, not a fine schedule.

Tandem over 34,000 on the Interstate by drivers relying on the 38,000 state figure or the 10% tolerance; NC SHP Motor Carrier Enforcement runs fixed scales on every Interstate corridor.
KPRA over 41 feet on a 53-foot trailer, particularly on trailers slid deep for a nose-heavy load.
Non-primary-route operation with a 53-foot trailer — the 53-foot allowance is for primary highway routes; secondary roads may be restricted.

North Carolina bridge law FAQ

Is North Carolina's tandem limit really 38,000 pounds?

G.S. 20-118(b)(2) says the tandem-axle weight shall not exceed 38,000 lb. Federal law caps tandems at 34,000 on the Interstate, and the same statute keeps the 34,000 / 36-foot rule. Plan on 34,000 on Interstates and verify with NC SHP how the state figure is enforced.

What does North Carolina's 10% tolerance cover?

G.S. 20-118 allows exceeding the maximum and inner axle-group limits in subsection (b)(3) by 10%. We could not confirm from the text whether it extends to the single-axle, tandem, or 80,000 gross figures; verify with NC SHP before relying on it.

What is North Carolina's kingpin-to-rear-axle limit?

41 feet from the kingpin to the rearmost axle, or to the midpoint between the two rear axles of a tandem, for semitrailers over 48 feet on primary highway routes (G.S. 20-115.1).

Does the bridge formula apply in North Carolina?

Yes, as a table of maximum weights by axle-group spacing in G.S. 20-118(b)(3), topping out at 80,000 lb.

Sources

This page is a driver's summary, not legal advice. Statutes are quoted or paraphrased from the sources listed; where we couldn't verify a figure from an official source we've said so.