CDL Pre-Trip Inspection – Rear of Tractor & Trailer

Mud Flap
- Must be properly mounted & secured; prevents debris projection and reduces spray in wet conditions.
- No visible damage (tears, warping, missing chunks) and must fully cover the tire width.
- Material integrity crucial for DOT compliance and to avoid road-going projectiles.
Lights / Reflectors
- All bulbs and reflective surfaces need to be intact: not cracked, damaged, or missing.
- Functional test: activate brake lights, tail lights, and turn signals; verify proper color (red to rear, amber if side-mounted under trailer).
- Significance: Visibility to following traffic; required by FMCSA §393.11.
Trailer Frame / Cross Members / Landing Gear
- Inspect for cracks, broken welds, bends, or corrosion.
- Landing gear must be fully raised, handle secured, and support feet free of damage.
- Structural soundness ensures trailer can bear rated loads without failure.

Lights / Reflectors / ABS Indicator
- Must be mounted securely, correct amber color on sides.
- ABS lamp should illuminate at start-up and extinguish during travel, confirming system health.
Sliding Tandem Assembly
- Rails and locking pins free of damage; pins must be fully engaged.
- Release arm straight, seated, and safety latch applied.
- Proper engagement prevents axle-shift during braking, maintaining legal bridge weight distribution.

Spring Mounts / Hangers (Front & Rear)
- Firmly attached to frame via bolts or rivets; no cracks or missing hardware.
- Failure here can cause axle misalignment and increased tire wear.
Leaf Springs
- Check every leaf: none cracked, shifted, or scissored (mis-aligned leaves).
- Missing leaves violate suspension GAWR limits and can trigger OOS (out-of-service).
Torque Rods / Radius Rods
- Securely mounted, straight, bushings intact; restrains axle wind-up during acceleration/braking.
U-Bolts
- Tight, unbroken, nuts and washers present; look for shiny threads or rust trails indicating looseness.

Air Hoses (Service & Emergency Lines)
- Flexible, no abrasions or bubbles; listen/feel for air leaks.
Brake Chambers
- Mounted securely with clamps tight; shell not dented or corroded; no audible leaks.
Slack Adjuster & Push-Rod
- With brakes released, manual pull should not exceed 1\,\text{in} travel; over-travel implies out-of-adjustment brakes.
- No missing clevis pins, cotter keys, or excessive angle (>90° at full application).
Brake Drum
- Free of cracks/heat-checking; inner surface smooth; no oil/grease contamination.
Brake Shoes / Linings
- Minimum thickness: steer 4/32'', driveline/tandem 2/32'' (regulatory threshold).
- No rivet head contact, no oil soaking, equal wear on both shoes to prevent pull.

Tires (I.C.D. Method)
- Inflation: verify with calibrated gauge; ±10 psi variance may reduce tire life by 15 %.
- Condition: no cuts, bulges, or cord exposure; even tread wear across face.
- Depth: not less than 2/32'' on non-steer axles; measure with tread gauge in major grooves.
- Valve stem straight, capped, no audible leaks.
Bud/Dual Spacing
- Even gap between duals; ensure no debris (rocks, chain, lumber) lodged which could puncture tire or fly out.
Rim
- No bends, welding repairs, or cracks (especially from bolt holes to flange).
Lug Nuts
- All present, seated, and tight. Indications of looseness: streaking rust or shiny threads.
- Torque specs typically 450\text{–}500\,\text{ft·lb} for 22.5-inch wheels.
Axle Seal (Inner & Outer)
- Dry exterior hub; no fluid drips or spray pattern on wheel.
Second Axle Statement
- Point to rear axle and verbalize: “I will inspect this axle the same way.” — satisfies complete-circle pre-trip requirement.

Mud Flaps
- Same criteria as front: secure, undamaged, width coverage of both tires.
Lights / Reflectors / Rear Conspicuity Tape
- Tail, brake, turn, 4-way flashers, license lamp operational; red color to rear.
- DOT-C2 retro-reflective tape continuous across ICC bumper and lower side rails for nighttime visibility.
Doors & Ties (Roll-up or Swing-type)
- Hinges lubricated, no missing bolts/pins; handles latch positively.
- Door seals intact to preserve cargo environment and block exhaust.
- Door-tie backs or keeper hooks present to secure open doors during loading.

All items align with FMCSA 49 CFR Part 393 (Parts & Accessories Necessary for Safe Operation).
Daily pre-trip documentation on DVIR (Driver Vehicle Inspection Report) reduces liability and is mandatory before operating a CMV.
Proper maintenance prevents CSA (Compliance, Safety, Accountability) points, fines, and possible OOS orders.

Neglecting inspections endangers public road users, the driver’s livelihood, and company reputation.
Minor issues (e.g., missing mud flap, loose lug nut) can escalate to catastrophic tire blowouts or loss of vehicle control.

Use the I.C.D. acronym when checking tires (Inflation – Condition – Depth).
BBC for brakes: Brakes (hoses & chamber), Balance (slack adjuster), Contact (shoes/drum).
“BBLL – Bud, Bolts, Lug, Leaks” for wheel area quick recall.
Practice a consistent clockwise pattern starting at driver front to ensure no area is skipped.

If a driver finds one broken leaf in a multi-leaf spring:
- Report defect, note on DVIR, and seek maintenance before dispatch; operating could violate 49\,\text{CFR}\,393.207(c) and lead to OOS.

Repeating this formula aloud reinforces memory and satisfies examiner expectations during CDL testing.