Lowboy Trailer Guide: Capacity, Dimensions, and Choosing the Right Configuration
The lowboy trailer is the workhorse of heavy equipment transport — but "lowboy" is a broad term that covers several distinct configurations with very different weight capacities and use cases. Understanding the difference between a standard 2-axle lowboy, a 3-axle lowboy, and a multi-axle RGN can save you money, prevent permit violations, and ensure your equipment arrives safely.
What Is a Lowboy Trailer?
A lowboy trailer (also called a low-bed or low-loader) is a flatbed trailer with a recessed well section that sits 18–24 inches above the ground — significantly lower than a standard flatbed (48–54 inches) or step deck (36 inches at the lower deck). This low deck height serves two critical purposes:
- It keeps tall equipment within legal height limits (typically 13.5–14 ft) without requiring special height permits
- It lowers the center of gravity for heavy loads, improving stability during transport
Lowboys are the standard choice for tracked excavators, bulldozers, motor graders, large compactors, and other heavy construction equipment that would exceed height limits on a standard flatbed.
Lowboy Trailer Configurations and Weight Capacity
Weight capacity varies significantly by axle configuration:
| Configuration | Payload Capacity | Max GVW | Best For |
|---|---|---|---|
| 2-Axle Lowboy | ~40,000 lbs | ~80,000 lbs | Compact excavators, small dozers, skid steers |
| 3-Axle Lowboy | ~60,000 lbs | ~100,000 lbs | Standard excavators, mid-size dozers, motor graders |
| 4-Axle Lowboy | ~80,000 lbs | ~120,000 lbs | Large excavators, large dozers, compactors |
| Multi-Axle (5+) | 80,000–200,000+ lbs | Varies | Mining equipment, large cranes, superloads |
Important distinction: A trailer's structural "ton rating" (e.g., "55-ton lowboy") refers to the structural capacity of the main beams — not the legal highway payload. The actual legal payload is calculated by subtracting the tractor and trailer tare weight from the maximum allowable GVW for the route. A 55-ton lowboy may only legally carry 40,000 lbs on a standard interstate route.
Lowboy vs. RGN: What's the Difference?
The terms "lowboy" and "RGN" (Removable Gooseneck) are often used interchangeably, but they describe different loading mechanisms:
- Fixed Gooseneck Lowboy: The gooseneck (front connection to the tractor) is permanently attached. Equipment must be loaded from the rear via ramps. This limits loading options for tracked equipment that can't easily back up a ramp.
- RGN (Removable Gooseneck): The gooseneck detaches, allowing the front of the trailer to drop to ground level. Tracked equipment (excavators, dozers) can drive directly onto the trailer from the front. This is the preferred configuration for most heavy tracked equipment.
When a carrier says "lowboy," ask whether it's a fixed or removable gooseneck — it matters for loading logistics.
Lowboy Deck Dimensions
Standard lowboy deck dimensions:
- Well length: 24–29.6 ft (standard); up to 53 ft for extended configurations
- Deck width: 8.5 ft standard; up to 10 ft for wide-load configurations
- Deck height: 18–24 inches above ground (varies by trailer and axle configuration)
- Ramp length: 8–12 ft (for fixed gooseneck models)
When to Use a Lowboy vs. Other Trailer Types
- Use a lowboy when: Equipment is over 10 ft tall (needs the low deck for height clearance), equipment is over 40,000 lbs (needs the weight capacity), or equipment is tracked and needs drive-on loading (use RGN specifically)
- Use a step deck when: Equipment is 8.5–10 ft tall and under 48,500 lbs — the step deck's lower rear deck provides clearance without the cost of a lowboy
- Use a flatbed when: Equipment is under 8.5 ft wide, under 13.5 ft tall, and under 48,500 lbs — legal-load moves are the most cost-effective
Permit Requirements for Lowboy Loads
Most lowboy loads require oversize or overweight permits:
- Loads over 80,000 lbs GVW require overweight permits in every state on the route
- Loads over 8.5 ft wide require oversize permits
- Loads over 13.5 ft tall require height permits (rare on a lowboy, but possible with tall equipment)
- Permit costs: $50–$400 per state for standard oversize/overweight loads
- Escort vehicle requirements: typically required for loads over 12 ft wide
IronHaul Logistics handles lowboy transport for heavy equipment of all sizes nationwide. Call (208) 495-2260, email [email protected], or use our online quote form to get a free, accurate rate for your load.
Common questions
How much weight can a lowboy trailer carry?
A standard 2-axle lowboy carries approximately 40,000 lbs of payload. A 3-axle lowboy handles about 60,000 lbs. Multi-axle configurations can carry 80,000–200,000+ lbs. The legal payload depends on the route's GVW limits, not just the trailer's structural rating.
What is the difference between a lowboy and an RGN trailer?
An RGN (Removable Gooseneck) is a type of lowboy where the front gooseneck detaches, allowing the trailer to drop to ground level for drive-on loading. A fixed gooseneck lowboy requires rear ramp loading. RGN is preferred for tracked equipment like excavators and dozers.
Do lowboy loads require oversize permits?
Most lowboy loads require overweight permits (for loads over 80,000 lbs GVW) and/or oversize permits (for loads over 8.5 ft wide). IronHaul handles all permit procurement as part of the move.
What is the deck height of a lowboy trailer?
Lowboy deck height is typically 18–24 inches above the ground, compared to 48–54 inches for a standard flatbed. This low deck height keeps tall equipment within legal height limits (13.5–14 ft) without requiring special height permits.
When should I use a lowboy instead of a step deck?
Use a lowboy when equipment is over 10 ft tall (needs the low deck for height clearance) or over 40,000 lbs. Use a step deck for equipment that is 8.5–10 ft tall and under 48,500 lbs — it's more cost-effective for lighter, moderately tall loads.
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