It’s easy to focus all your maintenance attention on the truck and forget that the trailer is half of your rig — and it carries the load. A neglected trailer is just as likely to strand you or fail an inspection as an engine problem, and trailer issues like worn brakes, bad tires, or faulty lights are some of the most common roadside violations. Here’s a practical trailer maintenance checklist to keep the back half of your rig road-ready.
Brakes
Trailer brakes do a big share of the stopping and are a leading inspection failure. Keep on top of:
- Brake lining and pad thickness
- Air lines, hoses, and chambers for leaks
- Slack adjusters and proper pushrod stroke
- ABS function and warning lamp
- Drums or rotors for wear and cracks
Tires & Wheels
- Tread depth and even wear across all positions
- Correct inflation — including inner duals that are easy to miss
- No cuts, bulges, or exposed cord
- Wheel and rim condition, with lug nuts tight
- No mismatched or improperly repaired tires
Lights & Electrical
Faulty trailer lights are one of the most common — and most avoidable — violations. Check:
- All tail, brake, turn, and marker lights
- Reflectors present and clean
- The 7-way connector and wiring for corrosion or damage
- That the truck-to-trailer electrical connection is solid
Coupling & Landing Gear
- Kingpin and fifth-wheel connection for wear and secure lock
- Locking jaws fully engaging
- Landing gear cranks smoothly and the legs are straight
- Safety chains or devices where required
Frame, Suspension & Body
- Frame rails and crossmembers for cracks, rust, or bends
- Springs, hangers, U-bolts, and air suspension components
- Mud flaps and splash guards intact
- Doors, latches, and seals in good condition
- Cargo securement points (rings, straps, rails) undamaged
Don’t Overlook Documentation
Just like the truck, the trailer needs current DOT annual and California BIT inspections, with records kept and available. A trailer that’s mechanically fine can still put you out of service on paperwork alone.
Make the Trailer Part of Your Routine
The simplest fix is to treat the trailer as part of every pre-trip walkaround and preventive maintenance visit — not an afterthought. Lights, tires, brakes, and coupling take only minutes to check and are the exact things that cause roadside stops. Catching them in the yard is far cheaper than on the shoulder.
ADM Services Trucks and Trailers On-Site
ADM Auto Services inspects and repairs both trucks and trailers on-site across the Bay Area and Central Valley — brakes, tires, lights and wiring, coupling, suspension, and full DOT/BIT inspections. We keep your whole rig road-ready and inspection-ready without a trip to the shop.
Need trailer service or an inspection? Call ADM Auto Services at 510.552.4926.
Jermiah King is the founder of ADM Auto Services. A trained diesel technician, he brings deep hands-on experience from the oil field and advanced manufacturing industries, including robotics and PLC work. After relocating to California in 2017, he founded ADM Auto Services to pursue what he loves most — keeping fleets running with expert, reliable vehicle service across the Bay Area and Central Valley.
