Trailer Dovetail Angle Calculator

Nothing strikes fear into your heart like the sound of metal scraping across steel as you drive up the ramp. More times than not, it’s not the end of the world but it is a reminder from physics that horsepower doesn’t matter much and that geometry matter a lot. Most folks buy trailer ramps assuming they will work well on whatever they tow. And in reality, it probably won’t. What was the perfect fit for hauling a low profile car hauler becomes a parking brake for a skid steer with deep treads or a zero turn mower. A few inches of vertical clearance and a few degrees in slope make all the difference between a smooth load and scraped up paint.

Before hitching up, use this to see how those restrictions work: This calculator lets you input your own configuration and then translates those basic measurements (tail length, deck height) into the kinds of angles your equipment will be able to manage. It tells you the approach angle (from the ground) and the dovetail angle (relative to the flat part of the deck). The difference matters: Even though a very steep ramp may not have a very gradual entry, that doesn’t mean the dovetail itself won’t be long enough for a smooth ride. And the hinge lip, the little bit of vertical rise where the fixed deck meets the ramp; is also factored in. That seemingly small feature is frequentely exactly where low-clearance cars and mower decks catches. Scratch one of those and you’re sorry.

How to Load Your Trailer Safely

A typical tilt on an equipment trailer would be something in the five- to ten-degree range. For cars, it’s going to be a bit flatter… Typically three to five degrees; since vehicles rides lower to the ground with limited approach clearance. Steeper will work for heavy stuff such as skid steers; however, they create different issues of their own. Tracks are shorter and wider than a set of rubber tires, bridging gaps in a unique way. You may think a slope will be okay until you hit something and get a track stuck in the gap due to a too-tight breakover radius.

The reference table on the calculator presents these familiar ranges so that you know where your trailer fits into the norm for what’s used throughout the trade. Outside the safe bands? Time to change tactics instead of forcing the load. There are quite a few variables in this equation and surprisingly, surface traction is one of them. Dry diamond plate steel has great bite. But wet paint will make it feel like you’re on an ice rink first thing in the morning. Wood decks offer decent grip but they’ll warp and crown with age, slightly affecting your actualy tail height. Aluminum is light but flexes under heavy point loads so that slight angle change can mean a scrape on a close call day. Don’t assume the best-case scenario, think about the worst case.

It is not the ideal afternoon on your driveway. Real world loading doesn’t occur on perfectly flat concrete, so the calculator has safety allowances built-in for measurement variation and uneven surfaces. Half the battle is measurement. Guys will measure the height of their deck without a trailer on it and think they can just throw a two-ton tractor on there. Well, the trailer settles. The frame flexes ever so slightly. What you thought was an approach angle is now steeper. You thought your tail was going to be this high off the ground, but it’s not anymore. Whatever your loaded deck height is, measure from the ground up to the deck, or guess and give yourself a conservative margin. Better to plan a tight squeeze than find yourself underneath a rolling machine.

You’re going to want to get the thing on and you don’t want to do any damage getting it off. Run through the numbers and check the clearance margin. Slim? Drop your tire pressure a bit to make the transition softer or extend your ramps. A few minutes of planning prevents hours of bodywork repair later. That’s what it all boils down to; that first scrape sound you wouldn’t of even want to hear.