Clearances, Weight Limits and RV Routing

Published October 23, 2026 · Last reviewed October 23, 2026

Why this fails so often

Car maps are built to find the shortest or fastest path for a vehicle that fits anywhere a car does. They may carry some truck-route data, but they often miss local bridge heights, seasonal or posted weight limits, narrow roads and low-hanging branches. Even good RV routing is only as good as its data, and roads change: resurfacing can lower a clearance, a temporary structure can narrow a lane, and a posted limit can be new. Treat any route as a draft until a second source agrees.

Most strikes happen at the end of a trip, in an unfamiliar town, when a driver trusts the screen and is tired. A low-clearance bridge ahead can have no room to stop and no way to turn around.

Know your numbers

Write down these, and keep them on the dash where you can see them: loaded travel height, including everything on the roof; overall length; width with mirrors; and your gross weight from a weigh ticket. Height is the number people get wrong, because they quote the brochure figure, forget the roof air conditioner or a satellite dish, or add a bike rack or a roof box after buying. Re-measure after any change.

Route check procedure

1. Measure the full height of your rig as it is loaded for travel, including air conditioners, vents, antennas, satellite dishes and anything on the roof, then write the number down where you can see it.
2. Note your gross weight from a scale ticket and your overall length, width and, for combinations, your turning behavior in tight corners.
3. Plan the route in an RV-specific routing tool, or on a road atlas written for large vehicles, and compare it with a second source.
4. Open your state’s 511 site, or dial 511, for each state you will cross and look for height, weight, construction and closure notices on your route.
5. Phone the tunnel operator, the county road department or the state DOT office for any restriction you cannot confirm online, and ask about propane rules at tunnels.
6. Choose the larger-margin route when sources disagree, and scout the last mile to the campground on a map or by phone before you arrive.

Rig sensitivity

Rig: Van / B-class Low for height and weight, though a high-top van still fails at some garages and low arches. Rig: Class C, Travel trailer Moderate; the cab-over or roof gear sets the limit, and the trailer swings on corners. Rig: Fifth wheel, Class A High: tallest, heaviest and longest, and a Class A with a towed vehicle has the least room to back out of a mistake.

Decisions, in priority order

Action

Measure the loaded height and keep it displayed. Add a margin to every posted clearance you compare it with.

Why it helps

A rig that is a few inches under a sign can still hit it if the road has a crown, the suspension bounces, or the sign is out of date.

Verification

A tape measure reading from the ground to the highest point, taken with the rig at travel weight, matches the number on your dash.

Action

Use an RV or large-vehicle routing tool and enter your real dimensions, then cross-check the result against a second route source.

Why it helps

A routing tool that knows your height and weight avoids many problems. A disagreement between two sources shows you where to look closely.

Verification

Both sources agree on the main roads, and any difference has been looked up on the state 511 site, by dialling 511, or with a phone call to the DOT.

Action

Check weight limits and restrictions on bridges and local roads through the state DOT or the county road department. Be careful with seasonal limits on rural roads.

Why it helps

Posted limits protect structures, and driving past one may bring a penalty or damage the road. Your gross weight is more than the dry weight on the brochure.

Verification

You hold the current figure from an agency, not a map, and your weigh ticket sits under it. Phone the office if the site does not answer.

Action

Ask the tunnel operator about propane before using any tunnel. Some tunnels limit or ban vehicles with propane, or require the tanks to be shut off.

Why it helps

Rules about hazardous materials in tunnels exist and vary by tunnel. Finding out at the portal leaves no good choice.

Verification

You have the operator’s answer for that tunnel, or you have planned a route that avoids it. See the propane system guide for the shut-off steps.

Action

Plan the last mile as carefully as the highway. Look at the approach to the campground, the turn into it and the interior roads, and phone the office to ask about low trees and tight turns.

Why it helps

Many access problems appear in the final mile, where highway tools fail and where you may be tired and in the dark.

Verification

The office confirms your length and height fit the entrance and your assigned site, and you arrive in daylight. Rig: Class A, Fifth wheel

If you misjudge a clearance

Do not drive on. If you are unsure whether you fit, stop before the structure, put the flashers on, and walk it or call for help. If you have already stopped under a bridge, do not push forward. Back out carefully with a spotter, or ask the local authority for help. A strike can cost your roof, your air conditioner, and the bridge owner’s repair bill. Related site-level checks are in the site fit guide.

How it works

Routing software works from a map database with attributes attached to each road segment: speed, direction, class, and sometimes height, weight or truck restrictions. A car profile ignores most of those attributes. An RV or truck profile reads them, but only the ones the database contains, and for many small bridges, tunnels and local roads the data is incomplete or out of date.

That is why verification comes from more than one place. The state agencies that own the roads publish restrictions, closures and construction through their 511 services, which you can reach by web or by dialling 511. County road departments handle local weight limits and seasonal rules. Tunnel and bridge operators set their own entry rules, including those for hazardous cargo such as propane. Each is the original source for its own piece of the puzzle.

Turning is a separate problem from height and weight. A long rig needs more room to turn than its wheelbase suggests, because the rear wheels follow a tighter path than the front and the body overhangs. A trailer cuts the inside of corners, and a long overhang behind the rear axle swings wide the other way. Roundabouts, gas station driveways, and narrow historic streets are where rigs get stuck. When a route has several tight turns near the end, a phone call and a look at satellite imagery often shows whether an alternative is safer.

Worked example

Suppose, purely as an illustration, you drive a Class C motorhome that you measured at about 11 feet 4 inches loaded, and you have taped that number to the dash. You plan a route to a small-town campground, and your routing tool shows a short cut through a historic district.

You check the state 511 site and find no construction notice, but the satellite view shows an old stone railway underpass. You call the county road office, which says the posted clearance there is lower than your height. You choose the longer route on the state highway, which adds about 12 miles.

On arrival you phone the campground to ask about the entrance and confirm a pull-through site that fits your length. The extra 12 miles of fuel cost far less than a roof repair. The figures are made up to show the sequence: measure, route, cross-check, verify with an agency, and choose the margin. The verification in each step is a second source, not a hope that the first was right.