Can a road case and a protective case be used interchangeably?

A: Briefly. A protective case is built for one shipment, a road case for a hundred handlings: replaceable guards, a reinforced housing, a stacking step.

Does a worn guard mean scrapping the case?

A: No. Guards swap with four to six screws; an enlarged hole needs a sleeve or one size up.

Why is a four-wheel case not rated at four times one wheel?

A: A threshold leaves only the diagonal pair down, so rating at three wheels keeps the margin.

Is three tiers a hard limit?

A: The usual limit. Drop to two with heavy equipment; empty cases can go four high if strapped as a block.

Can wheels be added later?

A: On an injection-molded case yes; on a rotomolded one only if a housing platform was molded in. ---

What Is a Road Case: Corners, Wheels and Stacking

Quick answer: A road case is a one-piece shell built to be loaded, stacked and reopened hundreds of times, and three positions decide whether it survives: corner guards, wheel set, and the step pressed into the lid for stacking.

What a road case is, and how it differs from a protective case
Corner guards: the only part allowed to wear through
Wheels: diameter, housing and brake
Stacking: the lid step and the load ribs
Holding the load inside, marking the outside
FAQ

1. What a road case is, and how it differs from a protective case

A road case is the touring trade's name for a case that travels repeatedly: not one shipment, but a hundred loadings in a season. Plywood with aluminium extrusion takes any size but weighs more and seals poorly; a one-piece rotomolded shell weighs thirty to forty percent less and carries a full-perimeter gasket. The difference is not wall thickness but load path.

Item	Plywood and extrusion	One-piece shell
Load path	Extrusion, ball corner	Guard, wheel housing, lid step
Sealing	Gasket in a jointed frame	Full-perimeter gasket
Weight	Higher	Thirty to forty percent lower

2. Corner guards: the only part allowed to wear through

The four bottom corners take the hardest duty: dragged into a truck, set down hard, crushed in a stack, so they are separate parts screwed to the corner post and replaced alone. A shell radius of 15 to 25 mm needs the guard wrapped 15 mm onto the wall; stop at the tangent and wear migrates onto the shell.

Position	Form	What fails first
Four bottom corners	Separate guard, screwed	Edge worn through
Four top corners	Thickened molded pad	Pad crushed, lid dished

Road Case in black, lid open and lying flat, foam cut into pockets for microphones and cables, corner guards and two castors in frame

3. Wheels: diameter, housing and brake

Wheel diameter sets threshold ability: 50 mm must be lifted over a 20 mm lip, 75 mm rolls over it, 100 mm is easier on gravel. Polyurethane rolls well indoors, PP is cheap and loud, TPR is quiet but short-lived. A wheel is rated 30 to 50 kg, yet a four-wheel case is rated at three times one: a threshold leaves only the diagonal pair down.

Diameter	Ground	Rating per wheel
50 mm	Indoor floors, truck beds	30 kg
75 mm	Concrete, thresholds	40 kg
100 mm	Grass, gravel, sites	50 kg

4. Stacking: the lid step and the load ribs

Stacking works on a step, not a flat face. The lid is pressed with a recess 8 to 12 mm deep, 2 mm larger than the base, so the case above drops in; without it, cases slide at the first bump. Two to four ribs spread load into the side walls, and four pads under the base carry it down the corner posts, not through the lid centre. Three tiers empty, two loaded; acceptance stacks three tiers for twenty-four hours and fails above 2 mm.

Road Case from above, the recessed step and molded handle forming two levels, a second identical case half lost in shadow

5. Holding the load inside, marking the outside

Foam pockets are cut 3 to 5 mm shallower than the equipment so the lid compresses it; heavy items get a plate and strap so foam never carries alone. Dividers are 9 mm plywood dropped into wall slots, and in a layered case they also brace the stack. Marking drives turnaround: a number on the front and both ends, tier limit and centre of gravity on the lid. Molded characters last a season; paint is gone by the third load.

Road Case, lid open on an old timber bench, cables coiled in foam beside white power blocks, black cases with aluminium edging stacked behind

Road Case stock: five tiers of dark grey cases on a timber pallet, two black straps running vertically, corner guards aligned layer by layer

Conclusion

The differences in a road case hide in three places: whether guards can be replaced, wheels dragged, the lid step holding the case above. Get those right and half a millimetre of wall barely matters; skip them and extra wall will not last a season. Specify a road case from those three.

This article covers container-side specifications and design implications only, not the handling, loading or use of the contents.