Will My Rig Scrape?
Steep driveways, campground entrances, and ferry ramps scrape tails because of breakover — the combined angle of the slope change — not just one grade alone. Check your rig's departure angle against the transition before you commit.
1 · Your rig's departure angle
Departure angle is measured from horizontal, at your rig's lowest rear point (hitch ball, bumper corner, trailer tail, stabilizer jack). Bigger is better.
How to measure your overhang and clearance
- Find the rear axle center. On a tow vehicle, that's the truck's own rear axle. On a trailer, use its axle (or the center of a tandem-axle pair).
- Find your true lowest rear point. Usually the hitch ball, a rear stabilizer jack, a bumper corner, or the trailer tail itself — not necessarily the frame.
- Measure straight back from the axle center to that low point (overhang), and straight down from that point to the ground (clearance), rig sitting level and loaded the way you actually travel.
2 · The transition you're checking
A driveway meeting the street, a campground entrance, or a ferry ramp — pick how steep each side is. If you're only worried about one sharp crest (like a curb cut), leave the second grade at "flat."
3 · The verdict
Before you trust any of this
This is a geometry estimate, not a guarantee. Real transitions aren't clean two-plane geometry, and loaded suspension sag (especially tongue weight squatting a tow vehicle) eats into the clearance you measured empty. Always cross slowly, at a diagonal, and get out and look (GOAL) at anything unfamiliar. This tool is not professional advice — see our full disclaimer.
Gear that pairs with this calculator
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FAQ
What's the difference between departure angle and ground clearance?
Ground clearance is a single vertical measurement — how much air is under your lowest point on flat ground. Departure angle is about geometry at a slope transition: it's the angle, measured from horizontal, at which your rear overhang first touches the ground as you drive over a crest. A rig can have generous ground clearance on flat pavement and still scrape hard crossing a steep driveway, because a long rear overhang with that same clearance produces a shallow departure angle. Overhang length matters as much as clearance height — a short tail with modest clearance often out-performs a long tail with more clearance.
Does tongue weight or trailer loading affect this?
Yes, and this calculator can't see it. Tongue weight squats the tow vehicle's rear suspension and the trailer's own suspension, which reduces real-world clearance below the geometric number you enter. A softly sprung truck or a trailer loaded nose-heavy can lose an inch or more of clearance right where you need it most. If your margin from this tool is already tight, assume loaded, squatted clearance is worse than the number you measured empty.
What should I do if my rig is right on the edge?
Get out and look (GOAL) before committing — walk the transition and eyeball the actual gap your tail will need. Cross at a diagonal, one wheel at a time, rather than straight-on; this increases the effective angle your overhang sees at any instant compared to crossing the crest square-on with both sides at once. Go slowly. If a spotter is available, use one. And if the numbers are close, consider whether there's a shallower entrance nearby, or whether unhitching and backing a trailer in separately avoids the problem entirely.
Where do I find my rig's rated departure angle?
Trucks, SUVs, and overlanding trailers built with off-road use in mind often publish a departure angle spec in the manufacturer's brochure or owner's manual — search your exact trim and configuration. Most travel trailers, fifth wheels, and everyday tow vehicles don't publish one at all, which is exactly why this tool's "estimate from measurements" mode exists: measure your rear overhang and ground clearance directly and let the math do the rest.