Station 2 of 6 Load and stack
Bread Tray Cube-Out: How Tray Design and Loading Strategy Maximize Trailer Space
Contents: 6 sections
The most trays a trailer can hold on paper comes from three counts multiplied together: dolly columns across the trailer, dolly rows along it, and tray levels on each dolly. That is a geometric maximum, not a loading plan; restraints, clearances, weight distribution and the route take trays off it. You get more trays by orienting the dolly the right way on the floor, by using a tray whose stack increment matches your product, and by checking the door opening and weight before you plan to the ceiling. Use your own trailer’s measured inside dimensions; trailers of the same nominal length differ.
What limits how many trays a trailer can carry?
Four things:
- Floor area. How many dolly bases fit across and along the trailer floor.
- Height. How many tray levels fit between the dolly base and the lowest point overhead, including the door opening you load through.
- Handling limits. How tall a stack your people and equipment can build and move safely.
- Weight. The legal and equipment weight limits for the truck.
When a trailer is full by volume before it reaches its weight limit, it has “cubed out.” Whether that is true for your loads depends on your product, trays and truck, so check it with the weight step below rather than assuming it.
How do you calculate trays per trailer?
In four steps. The worked example uses round illustration numbers, not a standard trailer: an inside space of 630 inches long, 99 inches wide and 110 inches high, a door opening assumed at the same height, a dolly base 26 x 22.4 inches and 5.4 inches high, and a tray 4.95 inches tall with a 4.08-inch stack increment (the Rehrig Pacific 28 x 22 in its high position, per its product page). Replace every number with your own.
| Step | Formula | Example |
|---|---|---|
| 1. Columns across | Inside width ÷ dolly width across, rounded down | 26 in across: 99 ÷ 26 = 3. 22.4 in across: 99 ÷ 22.4 = 4 |
| 2. Rows along | Inside length ÷ dolly length along, rounded down | 22.4 in along: 630 ÷ 22.4 = 28. 26 in along: 630 ÷ 26 = 24 |
| 3. Dolly positions | Columns × rows, for each orientation | 3 × 28 = 84, or 4 × 24 = 96 |
| 4. Levels per dolly | ((Height available − dolly height − tray height) ÷ stack increment, rounded down) + 1 | ((110 − 5.4 − 4.95) ÷ 4.08) = 24.4, so 24 + 1 = 25 levels |
| 5. Geometric maximum | Positions × levels | 96 × 25 = 2,400, or 84 × 25 = 2,100 |
Sources for the table: tray height and stack increment from the Rehrig Pacific product page linked above; all other inputs are illustration values; the formulas are ours.
Two things the example shows. Orientation alone changes the count by 300 trays, because the 22.4-inch side fits four times across the width and the 26-inch side only three. And the height step uses the tray’s stack increment, not its outside height; using the outside height for every level undercounts levels.
What will the trailer actually carry?
Less than the geometric maximum. Plan with three numbers, each smaller than the one before:
- Geometric maximum. The table above: the most dolly positions and levels that fit the measured space.
- Securable load. What is left once the load can be restrained and moved: space for load bars or straps and access to fit them, wall and door clearance, dolly wheels and handles that stick out past the base, the lowest point of the door opening or any overhead fixture, the dolly’s rated capacity, and how the weight sits over the axles.
- Route load. What a real route carries: stops that need their product reachable in order, mixed products and tray models, and damaged or uneven floor space.
None of these reductions has a standard figure; they come from your trailers, your restraint system and your routes. Measure them once by loading a trailer to the securable load and recording the count, then compare with the route loads you actually dispatch.
The level count also cannot exceed what your crew can build. The stop point for stacking by hand, this guide’s screening rule, is set in setting the highest stack your crew builds by hand.
How do you check weight?
Multiply it out and compare it with your truck’s limits. Loaded weight is trays per trailer times the weight of one loaded tray, plus the dollies. Weigh a loaded tray of your heaviest product rather than estimating it. On the Interstate system, federal rules set “The maximum gross vehicle weight shall be 80,000 pounds except where lower gross vehicle weight is dictated by the bridge formula” (23 CFR 658.17); that is gross weight, truck included, so ask your carrier or fleet manager for the payload your equipment actually allows.
If the load is under the weight limit with space to spare, you are cubing out, and the levers below are worth working. If it is near the limit, adding levels will not help.
Which changes add the most trays?
The ones that change the three counts above:
- Match stack increment to product. Every unused inch of clearance repeats on every level. A tray with a smaller increment, or a lower stacking position, adds levels without touching the floor plan; choosing it is covered in choosing tray depth by product clearance.
- Try both dolly orientations. Run steps 1 to 3 both ways before you assume the usual one.
- Keep one dolly size per trailer where you can. Two dolly footprints on one floor rarely tile cleanly, and the gaps between them carry nothing.
- Plan empty returns separately. Nested empties take less height than loaded trays, so count a return load with the nest increment instead of the stack increment.
Where trays go after loading, from the dock to the store and back, is covered in the route from the production line to the shelf.
What is the quickest way to find lost space?
Run the table for a trailer you load today, using its real measurements and your real tray, then walk a loaded trailer and compare. If the count on paper is higher than the count in the trailer, the gap is in orientation, mixed dolly sizes, a height limit, or the securing and route reductions you have not measured yet. Keep the three numbers apart when you report capacity: a plan built on the geometric maximum will promise trays the trailer cannot carry. If the securable load is already what you dispatch, the next gain has to come from the tray’s stack increment.