Width between wheel arches: every base van in mm and inches, and what fits between them

The Fiat Ducato (and its Boxer, Relay and ProMaster twins) is the widest van between the rear wheel arches at 1,422 mm (56.0 in); a Ford Transit or Transit Custom has 1,391 mm, a rear-wheel-drive Sprinter 1,349 mm, a VW Transporter 1,244 mm and the small vans about 1,225 mm. Every van takes an 8 × 4 sheet flat on its bare floor. Only the widest take a double mattress between the arches once they are lined.

The width between the walls tells you whether you can sleep across the van. The width between the arches decides everything that sits on the floor: a floor-level or rock-and-roll bed, a bench, a pallet of tiles, the sheet goods you carry home. In most vans the arches are also where the bed frame, the water tank or the batteries end up, so it helps to know how big they are before you design around them.

The table: every base van, between the rear arches

Between arches, bare is steel to steel at floor level, from the planner’s van database: each platform’s arch depth is derived from the maker’s published “width between wheel arches” figure and checked against its load width (August–September 2026). Lined takes 30 mm off each arch for insulation and board, the planner’s default wall build-up. The arch box length and height are the planner’s estimates: makers publish them only in body-builder drawings, so measure yours before you build tight to it. The ticks are for an 8 × 4 sheet (1,220 mm) on the bare floor, a UK double (1350 mm) and a three-quarter rock-and-roll bed (1,205 mm) between lined arches.

Two rows need a caveat. The Toyota HiAce figure is an estimate: I found no published between-arch number for the current body. And twin-rear-wheel versions (the 5 t Sprinter, heavier Iveco Daily chassis) have much deeper arches and are left out of the table — the planner carries their own figure per variant.

Drive changes the arch, not only the floor

The Sprinter is the van where the drive matters most. Front-wheel drive has 1,411 mm between the arches; rear- and all-wheel drive 1,349 mm, because the driven rear axle needs a deeper arch and a taller arch box. That 62 mm is the difference between a double mattress at floor level and not. On the Transit, Crafter and Master the width is the same on every drive, but the rear-drive arch box is taller (and the floor higher) — see the FWD vs RWD post for what else changes.

What fits between the arches

• Sheet goods. A 2440 × 1220 or 4 × 8 ft sheet lies flat on the bare floor of every van in the table; the Transit Connect, Berlingo, HiAce and Caddy clear it by 10 mm or less. Buy your ply before you line the arches — afterwards only 8 of the 16 rows still take it flat. The plywood post counts how many you need.
• A floor-level double bed. A UK double (135 cm) fits between bare arches in Fiat Ducato, Mercedes-Benz Sprinter FWD, Ford Transit, VW Crafter, Renault Master, Ford Transit Custom; between lined arches only in Fiat Ducato, Mercedes-Benz Sprinter FWD. A US full (54 in, 137 cm) fits bare arches in Fiat Ducato, Mercedes-Benz Sprinter FWD, Ford Transit, VW Crafter, Renault Master, Ford Transit Custom; an EU 140 only in Fiat Ducato, Mercedes-Benz Sprinter FWD. Anything wider sits above the arches — the mattress-size post has every size against every van.
• A rock-and-roll bed. A 1,205 mm-wide seat-bed fits between lined arches in 10 of the 16 rows. In a Transporter it is 1,184 mm lined against 1,244 mm bare, which is why Transporter beds are three-quarter width and bolted to the floor between the arches, not over them.
• A Euro pallet (1200 × 800 mm) goes in lengthwise, 800 across, in every van; crosswise (1200 across) it fits between bare arches everywhere, by millimetres in the small vans.

The arch box: dead space or the best cupboard in the van

Each arch takes 224 mm off each side of a Ducato for about 1.20 m along the floor — 0.54 m² of floor in total; the arch-box column gives the estimate for every van. Built over, that floor comes back as storage. The common ways to use it:

• Bench or seat base on the arch. A bench box built over the arch gives a seat at the right height and hides the hump; it is also the usual anchor point for a belted seat’s frame — the seating post covers how much length a belted bench takes.
• Water tank. Wheel-arch tanks are moulded to wrap the arch and keep water low and close to the rear axle. A full tank adds its weight right where the rear axle carries it, so check the axle loads and size it with the water tank calculator.
• Shower tray or wardrobe base. A tray stepped over the arch, or a wardrobe whose floor sits on the arch, uses height that is otherwise wasted under a raised bed.
• Garage. Under a fixed bed the arches limit the garage width at floor level to the figures above — the garage post works out what bikes and boxes fit.

Measure your own van

Measure at floor level, steel to steel, at the narrowest point of each arch — usually its middle, where the bulge is deepest — and again 20 cm up, because arch boxes are not vertical. Then measure the arch box’s length along the floor and its height. In VanPlot you can type those three numbers into the Van inspector (the measured wheel arches fields), and every template, collision check and floor-level bed in the editor uses your arches instead of the estimate. If you would rather ask than check by hand, VanPlot AI (beta, included with the licence) can place the bed or bench you describe in your variant and report what the design checks flag — see checking a layout with AI.

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