When a load is too tall for anything else, it rides a lowboy. Its ultra-low deck sits just inches off the ground, buying the vertical clearance to move machinery that would otherwise blow past legal height limits.
Quick answer: A lowboy trailer has a very low deck — often 18–24 inches off the ground — built to haul extremely tall, heavy equipment under legal height. It's crane- or ramp-loaded and rated for heavy machinery, with axles added for heavier loads.
A lowboy drops the deck between two axle sets to the lowest practical height on the road. That extra clearance is everything: a machine that would stand 15 feet tall on a flatbed can ride legally on a lowboy, avoiding height permits and low-bridge reroutes.
Lowboys are built heavy — commonly rated from 40,000 lb up into the six figures with added axles. Where an RGN wins on drive-on convenience, the lowboy wins on sheer height clearance and load rating for the tallest, heaviest freight.
| Deck / well height | ~18–24 in |
|---|---|
| Usable deck length | 24–29 ft well |
| Legal payload | 40,000 lb base — 100,000 lb+ with axles |
| Max cargo height (legal) | ~11'6"–12' |
| Loading method | Crane-loaded (best height clearance) |
| Axles (base) | 2–3 |
Equipment that exceeds legal height on any other trailer
Heavy, tall industrial units
Crane-loaded machines needing low deck height
Tall welded and cast structures
Deck height is what decides most loads. The lower the deck, the taller the machine you can carry and still clear 13'6" without a height permit — which is why the heavy stuff rides in a well.
| Trailer | Deck height | Legal payload | Max cargo height | Pick it when |
|---|---|---|---|---|
| Flatbed | ~5 ft (60 in) | 48,000–52,000 lb | ~8'6" | Load is under legal height and width and can be loaded from any side. |
| Step-Deck | ~3.5 ft (42 in) lower deck | ~48,000 lb | ~10' | Freight is too tall for a flatbed but still under ~10'. |
| Conestoga | ~5 ft (60 in); ~3.5 ft drop-deck | ~44,000 lb | ~8' interior (~10' drop-deck) | Load needs weather protection but still has to be crane- or side-loaded. |
| Double-Drop | ~18–24 in in the well | ~45,000 lb | ~11'6" | Freight is tall enough to need a well, and may need extra length. |
| Lowboy you are here | ~18–24 in | 40,000 lb base — 100,000 lb+ with axles | ~11'6"–12' | Height clearance is the binding constraint and the load is crane-loaded. |
| RGN | ~18–24 in | 40,000–50,000 lb base — 150,000 lb+ with axles | ~11'6" | Equipment drives on and off under its own power. |
| Multi-Axle / Superload | Follows the base RGN / lowboy deck | 200,000 lb+ | Route-engineered | Weight exceeds what any single trailer can carry legally. |
Ranges cover standard builds — exact capacity depends on the trailer, the axle spacing, and the bridge formula on your route. Send dimensions and weight and we'll tell you which one your load actually needs.
Before trailer choice matters, the load has to be measured against the federal legal envelope. Stay inside it and the load moves as ordinary freight. Break any one of these and it becomes an oversize or overweight move that needs a permit, and often a routed corridor and escorts:
Height is where trailer choice earns its money. Cargo height is measured from the pavement, not the deck — so a 12-foot machine on a 5-foot flatbed stands 17 feet tall and is illegal everywhere, while the same machine in a 2-foot well stands 14 feet and clears most routes. That single difference is why heavy equipment rides on a lowboy or RGN instead of a flatbed.
Weight works the same way, but the ceiling is the federal bridge formula, not just the 80,000 lb gross — it governs how much weight may sit on a given axle group over a given distance. That's why heavier loads get more axles rather than a bigger trailer: spreading the weight across jeeps and boosters keeps each axle group legal. Some western states allow 14' height without a permit, and every state writes its own overweight rules, so we check the actual route before quoting rather than assuming the federal baseline.
A lowboy is a heavy-haul trailer with a very low deck between its axle sets, designed to move extremely tall, heavy equipment under legal height limits. It's the trailer of choice when clearance is the constraint.
Because the deck rides so low, a lowboy can often keep a load under the 13'6" legal height that would otherwise require height permits and rerouting. Exact numbers depend on the machine and the route — we check both before we quote.
If the equipment drives on and off, an RGN is usually faster. If it's crane-loaded and the priority is maximum height clearance and load rating, a lowboy. We'll match the trailer to your machine.
Yes — full oversize/overweight permitting, route surveys, and pilot/escort coordination across every state on the route.
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