Trailer Towing Laws by State: Speed, Width, Length & Lighting

Last reviewed: July 2026

The short answer: every state caps trailer width at 8’6″ (102 inches) — that number is set federally and states are not permitted to deviate on the National Network. Height is 13’6″ or 14′ depending on the state. Trailer length runs 35′ to 53′, and total combination length runs 50′ (New Jersey) to 85′ (Wyoming). California is the one state with a hard 55 mph limit for anything towing. Everything else varies, and this page has the numbers.

This is the reference we wish existed when we started shipping trailers to all 48 contiguous states. Federal figures come from FHWA’s Freight Management size and weight overview and the Code of Federal Regulations; state dimensional limits are compiled from the fifthwheelst.com 50-state equipment and size compilation and cross-checked against published width and height summaries. Where sources conflict we say so instead of picking one.

The Federal Baseline — What Is the Same Everywhere

Four numbers are effectively national and are the floor under every state table below:

• 102 inches (8’6″) width. Per FHWA, “no state may impose a width limitation of more or less than 102 inches” on the National Network. Mirrors and other safety devices don’t count toward the measurement. This is why essentially every production trailer in America is built to 8’6″ or narrower.
• 20,000 lb single axle / 34,000 lb tandem axle / 80,000 lb gross on the Interstate System, subject to the Federal Bridge Formula, which can require a lower gross weight depending on axle count and spacing.
• Lighting under 49 C.F.R. § 393.11 and FMVSS 108 — the same lamp schedule regardless of state.
• CDL thresholds under 49 C.F.R. § 383.91.

Anything wider than 102 inches, taller than the state’s height cap, or longer than the state’s length cap needs an oversize permit from every state you cross. Permits are per-state, per-trip, and frequently carry daylight-only, no-weekend, or escort-vehicle conditions.

Trailer Size Limits by State

“Max trailer length” is the trailer alone; “max combination” is tow vehicle plus trailer bumper to bumper. Where a state does not publish a standalone trailer length, the combination limit is the binding constraint. Overhang rules (front and rear) are separate and are not shown here.

Two things worth pulling out of that table. First, North Carolina’s 35′ trailer limit is the tightest in the country — a 40′ gooseneck that is unremarkable in Texas needs a permit in North Carolina. Second, New Jersey’s 50′ combination limit is the binding constraint in the Northeast: a crew-cab dually at roughly 22′ plus a 30′ trailer is already at the line.

If you are shopping a long deck, this is the moment to check your home state and your regular routes before you commit. A 40′ gooseneck trailer is legal without a permit almost everywhere; a 53′ flatbed is a different conversation in the states with 40′ trailer caps.

Towing Speed Limits

Most states apply the posted limit to vehicles towing trailers — there is no separate, lower “towing speed limit” in the majority of the country. But the exceptions are real and they are enforced.

California is the big one. Any vehicle towing a trailer is capped at 55 mph on every highway in the state, including interstates posted at 70. All three published sources we checked agree on this, and it is the single most commonly violated towing rule in America. California also restricts towing vehicles to the right-hand lanes on multi-lane highways.

Beyond California, published compilations disagree with each other enough that we will not print a 50-state speed table we cannot stand behind. What we can say with confidence:

• Washington is reported at 60 mph for vehicles towing trailers on certain highways by two independent sources.
• Michigan imposes a 55 mph limit on certain non-freeway routes for combinations — check the road classification, not just the sign.
• Oregon restricts combinations over 10,000 lb GCW to 55 mph on two-lane roads and generally confines towing vehicles to the right lane.
• Several states — Alaska, Arkansas, Nebraska, New Hampshire, South Carolina and Louisiana among them — are reported to have reduced trailer speed limits in the 45–55 mph range, but sources conflict on the exact figure and the conditions. Verify with the state DOT before relying on a number.
• A number of states post a lower limit for combinations over a stated weight (Ohio, for instance, for combinations over 8,000 lb). Read the signs — they are usually posted as a second line under the main limit.

Practical guidance from people who move trailers for a living: 65 mph is the sane ceiling for a loaded trailer regardless of what is posted. Most trailer tires below 16″ are speed-rated to 65 mph, and exceeding that rating is the leading cause of blowouts on cargo trailers and utility trailers running the interstate in summer heat.

Lighting and Conspicuity Requirements

Lighting is where roadside inspections start, because it is visible from behind at 60 mph. The federal schedule under 49 C.F.R. § 393.11 and FMVSS 108 is what nearly every state adopts by reference:

The 80-inch line is the one people miss. An 83″-wide enclosed car hauler needs clearance lamps, side markers and the three-lamp identification bar; a 77″-wide single-axle utility trailer does not. Add the 10,000 lb GVWR trigger and you get conspicuity tape on essentially every equipment trailer and dump trailer sold today.

A few states layer their own rules on top — most commonly requiring functioning lights on any trailer regardless of size, and requiring that the tow vehicle’s lights not be obscured by the trailer or its load. If your load overhangs the rear of the deck, most states require a red flag by day and a red lamp by night on the extreme rear.

Safety Chains

Published 50-state lists disagree on which states have an explicit safety chain statute — some show a dozen states with no requirement, others show chains required nearly everywhere. That disagreement is a documentation artifact, not a real loophole. Our guidance is simple: treat safety chains as mandatory in all 50 states.

North Dakota is the clearest illustration of why. N.D.C.C. § 39-21-32 allows safety chains in lieu of brakes on a trailer — chains are not a nice-to-have there, they are load-bearing legal equipment.

How to rig them so they actually work:

• Cross them under the tongue in an X. If the coupler releases, the crossed chains cradle the tongue instead of letting it drop and dig into the pavement.
• Leave enough slack to turn, no more. Chains that drag are chains that wear through and throw sparks.
• Rate them to the trailer. The combined working load limit of the pair should meet or exceed the trailer’s GVWR. This is where the cheap chain on a used trailer bites people.
• Use safety pins or latching hooks, not open S-hooks, on anything above a light utility trailer.

Gooseneck and fifth-wheel trailers are the one common exception — many states exempt kingpin and gooseneck-ball connections from the chain requirement because the coupling geometry itself is captive. Check your state; several still require them.

Mirrors

The majority of states require that a driver have a clear view to the rear, which in practice means extended or tow mirrors whenever the trailer is wider than the tow vehicle. The statutes are usually written as a performance requirement — “a clear view of the highway for a distance of at least 200 feet to the rear” — rather than a hardware spec, so aftermarket clamp-on mirrors are generally acceptable as long as they deliver the view.

If you are towing an 8’6″ livestock trailer or enclosed cargo box behind a pickup with factory mirrors, you almost certainly do not meet the standard. This is a cheap fix and a common citation.

Double and Triple Towing

“Triple towing” means a tow vehicle plus two towed units — an RV and a boat, a truck and a trailer and a second trailer. It is legal in a minority of states and heavily conditioned where it is allowed.

Two of the most-cited published lists disagree on several states. The following states appear on both lists as permitting triple towing, which is the set we would rely on:

Alaska, Arizona, Arkansas, California, Colorado, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, South Dakota, Tennessee, Texas, and Utah.

Several other states — Connecticut, Hawaii, Illinois, Maryland, Mississippi, North Carolina, Oklahoma, Pennsylvania, South Carolina, Vermont and Wisconsin — appear on one list but not the other. Verify with the state DOT before planning a route through any of them with two towed units.

Where triple towing is legal, the common restrictions are:

• Total combination length caps — typically 65′, 70′ or 75′. Nebraska caps at 65′; Wisconsin at 70′.
• Second unit must be recreational — boat, snowmobile, ATV trailer — in several states.
• First trailer must be a fifth wheel or gooseneck in some states, ruling out bumper-pull-plus-bumper-pull.
• License endorsements may be required.

License Requirements

Under 49 C.F.R. § 383.91, a Class A CDL is required for any combination with a GCWR of 26,001 lb or more where the towed unit’s GVWR exceeds 10,000 lb. That is the federal commercial standard and it applies to interstate commercial operation.

The complication is that several states impose non-commercial license classes for heavy personal towing at similar or lower thresholds — California’s non-commercial Class A for heavy trailers is the best-known example. Because these vary and change, check your own state DMV rather than assuming that “not for hire” means “no special license.”

Run the arithmetic before you buy. A 20,000 lb GVWR detachable gooseneck behind a 14,000 lb GVWR one-ton is a 34,000 lb GCWR combination with a towed unit well over 10,000 lb — squarely in Class A CDL territory for commercial use. A 14,000 lb tilt deck behind the same truck is 28,000 lb GCWR and also over the line. This surprises people who bought the trailer first.

Weight Limits and Where They Bite

The federal Interstate limits — 20,000 lb single axle, 34,000 lb tandem, 80,000 lb gross, all subject to the Bridge Formula — matter to most trailer owners in one specific way: axle weight, not gross weight, is what gets you at the scale. A 14,000 lb tandem-axle dump trailer loaded tongue-light can put well over 7,000 lb on the rear axle while the gross is still legal.

Off the Interstate System, states set their own limits and many have seasonal frost-law restrictions that cut allowable axle weights substantially in spring. If you haul in the northern tier, check frost laws in March and April.

Two habits solve most of this: load 60% of the cargo weight forward of the trailer’s axle centerline to keep tongue weight at 10–15% of gross for a bumper pull (15–25% for a gooseneck), and weigh the rig once, loaded the way you normally load it, at a CAT scale. One $15 ticket tells you more than any calculator. This matters most on truck beds and roll-off trailers, where the load position changes constantly.

Frequently Asked Questions

What is the maximum legal trailer width in the US?

8 feet 6 inches (102 inches) in every state. Federal law bars states from setting a width limit above or below 102 inches on the National Network, so the figure is effectively national. Mirrors and other safety devices are excluded from the measurement. Anything wider requires an oversize permit from each state you travel through.

Is there a special speed limit for towing a trailer?

In most states no — the posted limit applies. California is the major exception, capping any vehicle towing a trailer at 55 mph statewide, including on interstates posted at 70. Washington, Michigan and Oregon impose reduced limits in specific conditions. Regardless of the posted limit, most trailer tires are speed-rated to 65 mph.

How long can a truck and trailer be together?

Combination length limits range from 50 feet in New Jersey to 85 feet in Wyoming, with 65 feet being the most common. Maryland and the District of Columbia are also tight at 55 feet. Separate trailer-only length caps range from 35 feet in North Carolina to 53 feet in Iowa, North Dakota and South Dakota.

Are safety chains required in every state?

Treat them as required everywhere. Published state lists disagree on which states have an explicit statute, but chains are legally required in the large majority and universally recommended. Cross them in an X under the tongue, rate the pair to at least the trailer’s GVWR, and leave only enough slack to turn.

What lights does a trailer need to be legal?

All trailers need two red tail lamps, two red stop lamps, turn signals, a white license plate lamp, and reflex reflectors. Trailers 80 inches or wider additionally need clearance lamps, side marker lamps and three rear identification lamps. Trailers 80 inches or wider over 10,000 lb GVWR need retroreflective conspicuity sheeting.

Do I need a CDL to tow a heavy trailer?

A Class A CDL is federally required when the combination GCWR is 26,001 lb or more and the towed unit’s GVWR exceeds 10,000 lb. That applies to commercial operation. Several states also impose non-commercial license classes for heavy personal towing at similar thresholds, so check your state DMV before buying a large trailer.

Which states allow triple towing?

Roughly two dozen states permit towing two units behind one vehicle, including Alaska, Arizona, Arkansas, California, Colorado, Idaho, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, South Dakota, Tennessee, Texas and Utah. Restrictions on total length, unit type and license class are common, so confirm with each state DOT.

Disclaimer: This guide is general information, not legal advice. Towing laws change, dimensional limits are amended, and speed and permit rules are updated between legislative sessions. Your obligations depend on the state where the trailer is registered and on every state you travel through, and commercial operation adds federal requirements on top of state law. Confirm current requirements with your state Department of Transportation or DMV — and with the DOT of each state on your route — before you tow. HR Trailer Service LLC (Wickenburg, AZ) assumes no responsibility for errors or omissions in this summary.