Complete guide to double drop (lowboy) trailers — when to use one, dimensions, deck height, weight capacity, height clearance, permit requirements, and common loads.
return ( What Is a Double Drop (Lowboy) Trailer? A double drop trailer — commonly called a lowboy — is a specialized flatbed trailer with a deck that drops down between the gooseneck (front) and the rear axles, creating a low-profile well for hauling tall or heavy equipment.
The deck drops twice: once behind the gooseneck and once before the rear axles, forming a U-shaped profile when viewed from the side.
This design puts the loading surface as close to the ground as possible, which is critical for hauling equipment that would exceed legal height limits on a standard flatbed or step deck.
For flatbed haulers considering expanding into heavy haul or oversize work, understanding double drop trailers is essential.
This guide covers dimensions, weight capacities, when you need one, permit requirements, and common loads.
Double Drop vs Standard Flatbed vs Step Deck Understanding the differences between trailer types helps you choose the right one for each load: Standard Flatbed Deck height: 58-62 inches from ground Usable deck length: 48 feet (typical) Maximum cargo height: approximately 8 feet 6 inches (to stay under 13'6" total) Best for: Lumber, steel, building materials, palletized freight — loads that are not excessively tall Step Deck (Drop Deck) Upper deck height: 58-62 inches (front section, typically 11 feet long) Lower deck height: 36-42 inches from ground Lower deck length: 37 feet (typical) Maximum cargo height on lower deck: approximately 10 feet Best for: Tall equipment that fits within legal width and does not require the absolute lowest deck Double Drop (Lowboy) Well (main deck) height: 18-24 inches from ground Well length: 24-29 feet (varies by model) Maximum cargo height in well: approximately 11 feet 6 inches to 12 feet Best for: Tall heavy equipment — excavators, bulldozers, industrial machinery, transformers, generators The general rule: if your cargo fits on a standard flatbed without exceeding 13'6" total height, use a flatbed.
If it is too tall for a flatbed but fits on a step deck, use a step deck.
If it is too tall for a step deck, you need a double drop.
Each step down in deck height costs you usable well length, so only go to a double drop when you actually need the clearance.
Double Drop Dimensions in Detail Well (Main Deck) The well is the low center section where your cargo sits.
Standard well dimensions: Length: 24-29 feet.
Specialty lowboys can have wells up to 40 feet, but these are less common.
Width: 8 feet 6 inches (standard legal width).
Some lowboys have outriggers for wider loads, requiring overwidth permits.
Height from ground: 18-24 inches depending on tire size and suspension.
Mechanical lowboys sit lower than air-ride models.
Inside height (ground to legal limit): Approximately 11'6" to 12' of cargo height, keeping total vehicle height at or below 13'6".
Gooseneck The front section (gooseneck) rises from the well to connect to the tractor's fifth wheel.
Some lowboys have a usable gooseneck platform for ligh.
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