Maine trailer laws require you to register every trailer used on a public road, title it if it weighs more than 3,000 pounds unladen, equip it with brakes above that same threshold, add a safety chain, keep lights and reflectors working, stay within posted weight and size limits, and pass an annual inspection if it hits 7,001 pounds. Passengers cannot ride inside a trailer while it moves. Penalties run from a $25 minimum for overweight operation to a Class E crime for a trailer the current owner has never registered.
Registering and Titling a Trailer
Any trailer used or parked on a public road in Maine must be registered with the Bureau of Motor Vehicles before it hits the road. That applies to personal and commercial trailers alike.1Maine State Legislature. Maine Code Title 29-A 351 – Registration Required
Fees track the trailer’s weight. A trailer up to 2,000 pounds costs $10.50 for a half-year or $21 for a full year. At 2,000 pounds and over, the fee is $20 for a half-year or $40 for a full year.2Maine Secretary of State. Registration Fees Maine also offers semipermanent plates: $5 for trailers not exceeding 2,000 pounds gross vehicle weight and $12 for semitrailers, good for three years with no refund during those years.3Maine Legislature. Maine Code Title 29-A 512 – Semipermanent and Permanent Registration Plates for Trailers and Semitrailers
Titling is a separate step. Trailers and semitrailers with an unladen weight above 3,000 pounds must carry a certificate of title, and you’ll need proof of ownership when you apply — a bill of sale for a used trailer or a manufacturer’s certificate of origin for a new one. Registration alone is not enough above that threshold.
Brakes, Safety Chains, and Lights
Trailers and semitrailers must have working brakes on all wheels of every axle. Trailers at 3,000 pounds gross weight or less are exempt.4Maine State Legislature. Maine Code Title 29-A 1902 – Brakes If your trailer sits above that line, the brakes have to function before it goes anywhere.
Every towed trailer, semitrailer, or vehicle needs a safety chain or steel cable in addition to the hitch. The chain or cable must be at least 1/4-inch wire, and it has to be attached so the trailer cannot break away if the primary coupling fails. Truck tractor and semitrailer combinations using a fifth-wheel mechanism are the only exception.5Maine State Legislature. Maine Code Title 29-A 2385 – Protruding Objects and Trailers
Tail lights, brake lights, and turn signals must work and be visible from a reasonable distance. Reflectors are required for low-light visibility. A burned-out bulb or missing reflector will fail an inspection and can draw a citation at a roadside stop.
Weight Limits
Gross vehicle weight limits in Maine depend on how many axles the vehicle or combination has.6Maine State Legislature. Maine Code Title 29-A 2353 – Weight Limits
- Two-axle vehicle: 34,000 pounds
- Three-axle vehicle or combination: 54,000 pounds
- Four-axle vehicle or combination: 69,000 pounds
- Five or more axle combination: 80,000 pounds
- Three-axle tractor with tri-axle semitrailer: 100,000 pounds
Individual axles carry their own caps. A single axle tops out at 22,400 pounds, a tandem-axle unit at 38,000 pounds, and a tri-axle unit at 48,000 pounds. Within a tandem-axle unit, no single axle can bear more than 60 percent of the tandem’s total weight unless neither axle individually exceeds the single-axle limit.6Maine State Legislature. Maine Code Title 29-A 2353 – Weight Limits
Size Limits
Width, height, and length are all capped.
Total width, including any load projecting beyond the sides, cannot exceed 102 inches. Maximum height for the vehicle’s permanent or temporary structural parts is 13 feet, 6 inches from level ground. A load may extend up to 6 inches above that structural height and no more. Even so, you cannot legally drive under a bridge or overpass that lacks clearance for your vehicle.7Maine Legislature. Maine Code Title 29-A 2380 – Height and Width Restrictions
A single vehicle cannot exceed 45 feet in length. A combination generally cannot exceed 65 feet. A trailer or semitrailer can measure up to 48 feet if the distance from the rearmost tractor axle to the rearmost trailer axle is 38 feet or less, and in that setup the combination cannot exceed 69 feet overall.8Maine State Legislature. Maine Code Title 29-A 2390 – Maximum Length Limits
Annual Inspections
Maine requires annual safety inspections for trailers and semitrailers with a gross vehicle weight rating (or actual weight) of 7,001 pounds or more. Camp trailers are exempt.9Maine State Police. Safety Inspection of Trailers and Semi-Trailers in Maine For interstate commercial use, the threshold is a combined vehicle weight of 10,001 pounds. Intrastate commercial trailers face the same 10,001-pound combined trigger but also must exceed 3,000 pounds individually.
Inspectors examine air and electrical lines, frame and body condition, cargo securement, tail and brake lights, turn signals, reflectors, wheels, rims, hubs, tires, and any sliding tandem mechanisms. On double, triple, and full-trailer setups, they also verify safety chains and devices, pintle hooks, drawbars, and eye connections for cracks, excessive movement, and improper repairs. Any failed item has to be fixed before the trailer can pass and go back on the road.
Towing and Who Can Ride
Maine has no separate speed limit for vehicles pulling trailers. You follow whatever the posted limit is. Outside business and residential areas, though, a driver towing another vehicle must leave enough space behind the vehicle ahead that a passing car can safely merge into the gap.
The hitch or coupling has to be sound and rated for the load. The towing vehicle needs mirrors that show the trailer and the road behind it. And the safety chain or cable already described is required on top of the primary coupling.
Nobody may ride inside a camp trailer, mobile home, semitrailer, or any other trailer while it moves on a public road. There are four narrow exceptions:10Maine Legislature. Maine Code Title 29-A 2061 – Riding in Trailers
- An employee performing job duties for an employer
- A trailer used for farming or agricultural purposes
- A trolley trailer where all passengers are seated and the towing vehicle stays at or below 10 miles per hour
- A person with a disability in a vehicle needing road service when no other practical transportation is available
Riding in a trailer outside those exceptions is a traffic infraction, and it catches campers off guard every summer.
Penalties
Registration violations scale with how long the lapse has run:11Maine State Legislature. Maine Code Title 29-A 351 – Registration Required
- Expired 30 to 150 days: up to $50 for a first offense
- Expired 150 days or more: up to $100 for a first offense
- Any subsequent offense: up to $500
- Never registered by the current owner: Class E crime, which can carry jail time
Improper registration — a trailer registered in a way that doesn’t match its actual use or type — draws a fine of $200 to $1,000.11Maine State Legislature. Maine Code Title 29-A 351 – Registration Required
Operating a trailer above its registered weight is a separate infraction. The fine is twice the difference between the fee for the actual weight and the fee for the registered weight, with a $25 minimum. Private ways are exempt.12Maine State Legislature. Maine Code Title 29-A 2356 – Operation of a Vehicle Exceeding Registered Weight
Traffic infractions not specifically listed in the fine schedule carry a default fine of $146.13Maine State Legislature. Schedule of Amounts Due for Traffic Infractions Equipment violations like a missing safety chain, a non-functional brake light, or a failed inspection generally land here. Repeat offenders and drivers with multiple outstanding violations risk license suspension or trailer impoundment, and serious cases can land in court, where a judge may add penalties.