Most RV size rules never come up until the one trip where they do: a combined-length cap on a mountain route, a triple-towing ban at a state line with a boat trailer behind the fifth-wheel, a campground that cannot legally accept a rig over 40 feet. The limits are not hard to follow once you know them, but they are not uniform, and the number that matters, combined length, is exactly the one most owners cannot recite for the states they are about to drive through.

This table gives the four figures that actually govern a route: maximum single-trailer length, maximum combined length, maximum width, and whether triple towing is legal. Plan to the strictest state on your itinerary.

RV and Trailer Towing Limits by State (2026)

Maximum single-trailer length, maximum combined (tow vehicle + trailer) length, maximum width, and whether triple towing (pulling two trailers, e.g. a fifth-wheel plus a boat) is legal. Compiled from state DOT size-and-weight codes. 'Not set' means the state caps the combination length rather than the trailer alone. Height limit is 13'6" in most states (14' in the West). Special permits can raise several of these; verify with the state DOT before a trip.

The number that actually governs your rig

For most travelers the maximum combined length is the controlling limit, because it measures the whole setup, tow vehicle and trailer together, or motorhome and towed car. It ranges from a tight 50 feet in New Jersey and 53 feet in Mississippi up to 75 feet or more across much of the West, with Wyoming’s 85 feet the most generous in the country. A 40-foot fifth-wheel behind a full-size truck runs close to 60 feet combined, which clears most states but bumps against the low-cap states, so a coast-to-coast route needs planning around them.

The trailer-length column matters mainly for very long fifth-wheels and toy haulers. Where a state shows “Not set,” it regulates the combination rather than the trailer alone, so the combined column is your real limit. Width is nearly universal at 8 feet 6 inches, so it rarely constrains anyone; mirrors and awnings do not count against it. Run the numbers for your specific setup with our towing capacity calculator and read how to calculate towing capacity correctly so weight, not just length, stays legal and safe.

Triple towing, pulling a second trailer behind your fifth-wheel or travel trailer, is where states genuinely split. Roughly half permit it, the rest ban it outright, and a few sit in between: Arizona and Illinois allow it only with a fifth-wheel as the lead trailer, and Wisconsin requires a permit. Where triple towing is legal, the combined-length limit still applies, and several states publish a higher combined cap that applies specifically to triple tows (Indiana, Iowa, Kansas, and Utah among them). If you tow a boat or utility trailer behind the RV, map the triple-towing column before you commit to a route, because a single banned state can force a long detour.

Route planning around the strictest state

The rule that trips people up is jurisdiction: while you are in a state, that state’s limits apply, no matter what is legal back home. So the practical method is simple. List the states your route crosses, find the lowest combined-length cap and the triple-towing status among them, and build to that. If one state on the line is stricter than your rig allows, either reroute or check whether it offers an oversize trip permit. Our RV towing safety tips and weight-distribution hitch guide cover the handling side once the legal side checks out.

State DOTs adjust these codes periodically, and special permits can raise several of the limits shown. I keep this table aligned with the published size-and-weight codes, and the note above it carries the caveats. When in doubt for a specific trip, the state DOT’s oversize-permit page is the definitive source.

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