Fifth Wheels for Heavy-Duty Trucks & Trailers

Whether you’re moving step-decks, heavy hauls or full trailer systems, the coupling interface between truck and trailer is key. At Custom Truck One Source, our heavy-duty fifth wheels and associated coupling systems are engineered for maximum strength, fitment and safe operation under extreme duty cycles.

Why a Good Fifth Wheel Matters

The fifth wheel connects your tractor to the trailer—taking massive loads, dynamic motion, vibration and side forces. A well-engineered fifth wheel ensures correct alignment, reliable king-pin engagement, minimal lateral movement and reduced wear on both truck and trailer. A poorly matched or worn coupling system increases risk of instability, uneven loading, premature wear and unscheduled downtime.

How to Choose the Right Fifth Wheel for Your Application

When choosing a fifth wheel for a heavy-duty truck or trailer application consider:

• King-pin & trailer compatibility: Make sure it matches trailer king-pin size, mounting bolt pattern, height and offset to fit and articulate properly.
• Load rating & duty cycle: Choose a fifth wheel rated for your gross combination weight, trailer type (flatbed, low-boy, step-deck) and operation (haul, construction, transport).
• Slide/adjustment features: For variable trailer lengths or load shifts a sliding or adjustable fifth wheel may be required to keep weight balanced and axle loads compliant.
• Mounting & installation: Make sure it fits your frame rails, pin box offset and includes the correct hardware or mounting kit for installation.
  If you’re not sure which fifth wheel fits your application our parts team is here to help with fitment verification, part-number cross-reference and mounting support.

Maintenance Tips & Replacement Indicators

To keep the coupling safe and avoid failures monitor for:

• Excessive play or movement between the tractor and trailer—it may mean wear in the fifth wheel plate or king-pin bushing.
• Unusual noise, uneven wear or visible damage in the coupling area—it may compromise secure lock-up.
• Difficulty in trailer articulation, locking/unlocking or smooth pivoting—it may mean mis-alignment, worn components or improper lubrication.
• During trailer replacement or overhaul inspect the fifth wheel, king-pin, mounting bolts and locking mechanism—and replace worn parts before they fail.

Why Choose Custom Truck One Source* Heavy-duty fifth wheels and coupling components for trucking, vocational, haul, construction and transport fleets.

• Nationwide distribution and fast shipping to get you back on the road.
• Experienced parts staff with heavy-duty truck and trailer knowledge to ensure fitment, compliance and safe operation.
• Competitive pricing, good availability and filtering tools to help you find the right coupling system.

Shop Now

Browse our full line of heavy-duty fifth wheels—filter by load rating, king-pin size, slide, mounting kit or part number. Call 877-831-0572 to order or talk to our parts team.