Why body parts are low-density freight
A plastic bumper cover is a thin shell five to six feet wide and around 10 to 15 lbs. Boxed individually for a body shop, it ships in a carton of 15 to 20 cu ft. Hoods, fenders, door shells and radiator supports are steel or aluminum stampings with similar profiles: large, thin, curved, and easy to dent. Stack those cartons on an oversized skid and the result is around 1.5 to 3.5 PCF, class 250 to 300.
The rest of the aftermarket is different. Windshields on A-frame racks are dense; tires are moderate and usually floor-loaded; mufflers, exhaust kits and suspension parts are in between. A collision parts distributor's weekly replenishment often mixes all of these, and the light body-part skids decide whether the shipment trips a carrier cube rule.
Because collision repair runs on insurance timelines, body shops want parts in days, and distributors replenish branches on fixed weekly schedules. That rhythm makes aftermarket freight a recurring lane with a predictable profile, which is exactly the kind of freight that should be priced on its real cube once rather than corrected on every invoice. Three habits of the trade make it worse:
- Oversized skids. Bumper cartons do not fit a 48 × 40 pallet, so they ride on 80 or 96 in skids that are hard to stack.
- Pyramid tops. Mixed cartons built up unevenly leave a peaked top that nothing can sit on.
- Do-not-stack labels on everything. Understandable for painted parts, but it sends every skid to the 96 in imputation.
Typical automotive aftermarket handling units
| Unit | L × W × H (in) | Lbs | Cu ft | PCF | Class | Cubed to 96 in |
|---|---|---|---|---|---|---|
| Boxed bumper covers on skid | 80 × 48 × 72 | 280 | 160.0 | 1.75 | 300 | 1.31 PCF · 300 |
| Hoods and fenders on skid | 72 × 48 × 60 | 420 | 120.0 | 3.50 | 250 | 2.19 PCF · 250 |
| Windshields on A-frame rack | 72 × 40 × 60 | 1,050 | 100.0 | 10.50 | 92.5 | 6.56 PCF · 125 |
| Passenger tires, stacked on pallet | 48 × 40 × 72 | 520 | 80.0 | 6.50 | 125 | 4.88 PCF · 175 |
| Exhaust kits and mufflers | 96 × 40 × 48 | 600 | 106.7 | 5.63 | 175 | 2.81 PCF · 250 |
Weights are representative. The windshield and tire lines are not cube problems on their own, but both are routinely marked non-stackable, which costs them a class or two. Glass on an A-frame genuinely cannot take top weight, and a rack is usually loaded so the glass faces run parallel to the trailer sides, which limits flex when the trailer brakes and corners. A tire pallet with a flat, rigid cap often can, and tires are commonly floor-loaded on truckloads with no pallet at all, which removes the question entirely.
Run six bumper skids against XPO Item 233
- Safe — tariff cube, density and linear feet stay under the carrier's cube and linear-foot rules.
- Tier 1 — 350 cu ft or more under 3 PCF (XPO, Saia, ABF, Estes): synthetic weight of 6 lbs per tariff cubic foot.
- Re-bill — 750 cu ft or more under 6 PCF, or linear feet at the carrier's rule: book volume LTL or direct partial truckload.
Worked example: six bumper skids on XPO
A collision parts distributor sends six skids of boxed bumper covers 600 miles to a branch. Each skid is 80 × 48 × 72 in and 280 lbs, and each is marked do-not-stack. The account is with XPO (CNWY 199 Item 233: 350 cu ft under 3 PCF, 750 cu ft under 6 PCF).
Actual cube = 160.0 × 6 = 960.0 cu ft · Weight = 280 × 6 = 1,680 lbs
Density = 1,680 ÷ 960.0 = 1.75 PCF → Sub 2, class 300
Imputed density = 1,680 ÷ 1,280.0 = 1.31 PCF → class 300
Synthetic weight at 6 PCF = 1,280.0 × 6 = 7,680 lbs
Linear feet = 3 rows × 80 in ÷ 12 = 20.0 LF
Both Item 233 tiers apply and the load is over 12 LF. The carrier would rate 7,680 lbs against 1,680 real pounds, more than four and a half times the scale weight.
| Option at 600 miles | Indicative linehaul |
|---|---|
| Class 300 LTL as booked | $690 |
| After Item 233 re-rate and W&I fee | $1,775 |
| Same parts nested to 56 in and stackable, re-rated | $1,062 |
| Spot volume LTL on 20 LF | $686 |
| Direct partial truckload on 20 LF | $788 |
The nested line is worth reading closely. Bumper covers of the same model nest inside each other. Re-packed so the same 280 lbs builds to 56 in with a flat cap, each skid is 80 × 48 × 56 ÷ 1,728 = 124.4 cu ft, or 746.7 cu ft for six. That is 2.25 PCF and class 250, and because the skids are stackable and under 60 in, there is no imputation. The load falls 3.3 cu ft under XPO's 750 cu ft tier, though it still trips the 350 cu ft / 3 PCF tier. Better packing alone takes about $713 off the re-rated bill. The volume LTL quote at about $686 or the partial at about $788 takes off roughly $990 to $1,090, without changing the packing at all.
Packing body parts and glass
- Nest like parts. Bumper covers, fender liners and some hoods nest when they are the same part number. Use foam or cardboard between nested painted parts.
- Build flat tops. Put the largest cartons at the bottom and finish each skid with a full-size cap. A flat top is what lets a carrier load another skid on it.
- Size skids to the cartons. An 80 × 48 skid under 76 in cartons avoids overhang; overhang both damages parts and adds measured length. See pallet overhang and density.
- Ship glass on racks, edge-down, strapped. A-frame racks are returnable; plan the empty-rack return as a separate light shipment.
- Floor-load tires on truckloads. On partial and full loads, laced or stacked tires without pallets fill the trailer best. On LTL they need pallets and caps.
- Write every skid's dimensions on the BOL. Carriers measure body-part skids almost every time; the BOL checklist lists what to include.
Equipment and delivery considerations
Aftermarket freight usually moves warehouse to branch or warehouse to body shop. Branches have docks; body shops often do not.
| Delivery type | Typical need | How we tender it |
|---|---|---|
| Distribution center to branch | Dock-to-dock, recurring weekly | Volume LTL or a scheduled partial on the same day each week |
| Branch to body shop | Liftgate, small trucks, tight streets | Local LTL or box truck service |
| Glass on racks | Forklift at both ends, rack return | Partial or dedicated, with the return leg quoted |
| Tire loads | Floor-loaded, long load times | Full or partial truckload with loading time agreed |
A recurring weekly replenishment of 6 to 12 skids is a strong case for a standing partial or volume LTL arrangement. The cube and linear feet are predictable, so the rate can be set on the real profile instead of re-rated every week.
Returns are the other half of the lane. Branches send back damaged or wrong parts, empty glass racks and cores (used starters, alternators, calipers and similar parts returned for remanufacturing) to the distribution center. Glass racks coming back empty are light and awkward; cores are dense and usually ride in gaylords or steel bins. Pairing the return freight with the outbound replenishment on the same partial truck, as a backhaul from the branch, is often cheaper than booking each return as its own LTL shipment, and it keeps the racks moving back to the glass supplier on a predictable cycle.
Which mode Cubic Transport tenders auto parts on
Mixed small orders under 350 imputed cu ft move standard LTL with honest dimensions. Body-part replenishment from about four skids up goes on a spot volume LTL quote built on linear feet, or a direct partial when painted parts or glass are on board. Tire loads and large program shipments go 53 ft truckload, floor-loaded.
