A truck tyre is inflated to a high pressure, around 9 bar. The exact value depends on the tyre and the load, and is given in the tyre manufacturer's tables. You therefore need a compressor that goes above that pressure: at least 10 bar, like the S 220 PM, and 12.5 or 13 bar if you want a real margin.
Inflation is only one of the jobs in a truck workshop. This article focuses on that point alone: the pressure and the air you need to inflate truck, coach or trailer tyres.
Why an 8 bar compressor is not enough
Air always flows from the higher pressure to the lower one. As network pressure gets close to the tyre pressure, inflation slows down, then stops. With an 8 bar compressor, a tyre at 9 bar will never fill.
Two losses add up between the compressor and the valve:
- The pipework and the hose, especially if the tyre bay is far from the compressor.
- The compressor's control. A compressor does not stay at its maximum pressure: it restarts or speeds up when pressure falls. Check that the lowest pressure in its cycle stays above the target tyre pressure.
In practice, a 10 bar compressor inflates a tyre to 9 bar, with little margin. A 12.5 or 13 bar version fills faster at the end and tolerates a longer network.
How much air does a truck tyre need?
The calculation is simple: air to supply = internal volume of the tyre × pressure rise in bar. For the example, take a tyre with an internal volume of about 100 litres. This is an assumption: replace it with the value for your tyres.
- Full inflation, from 0 to 9 bar: 100 × 9 = 900 litres of air.
- Topping up a tyre that has dropped from 9 to 7.5 bar: 100 × 1.5 = 150 litres.
- Checking a set of 12 tyres, each topped up by 0.5 bar: 12 × 100 × 0.5 = 600 litres.
These volumes are small next to the flow of a screw compressor: the S 220 PM delivers 3.2 m³/min at 10 bar, or 3,200 litres per minute. Flow therefore matters less than pressure. What slows inflation down is the valve and the inflator. For seating the bead of a tubeless tyre, the receiver's reserve is what counts: we explain it in inflating and seating a tractor tyre.
Which compressor should you choose?
| Situation | Recommended model | Pressure and flow |
|---|---|---|
| Truck workshop, inflation among other tools | S 220 PM, 22 kW screw | 10 bar, 3.2 m³/min at 10 bar |
| Workshop that wants pressure headroom | S 150 in its 13 bar version | 1.6 m³/min at 13 bar |
| Small workshop, occasional inflation | E 75 HP, two-stage piston | 12.5 bar, 1.05 m³/min, 300 L receiver |
| Vehicles stuck in the yard | M 220, mobile screw | 12.5 bar, 2.0 m³/min, twin receiver totalling 180 L |
Higher pressure has a cost: a compressor delivers less flow and uses more electricity at 13 bar than at 10 bar. If inflation is the only high-pressure need, keep the rest of the network at the pressure your tools need. Our article on how to calculate compressor pressure covers this choice.
The M 220 rolls on its wheels to the vehicle. You need a 380 V three-phase socket where you use it.
Safety at the inflation bay
- Never exceed the manufacturer's pressure. A 12.5 or 13 bar compressor can exceed it: fit a pressure regulator at the inflation bay.
- Inflate a demounted tyre in an inflation cage or a restraint device, following the equipment's manual and the safety rules that apply.
- Stay out of the tyre's path. Use an inflator with a clip-on chuck, a hose long enough and a remote gauge.
- Check pressure cold, with a reliable gauge, and use suitable valve extensions on twin wheels.
- A tyre that has run flat or very underinflated must be inspected before it is reinflated, following the manufacturer's instructions.
Water, the enemy of wheel rims
Moist air leaves water inside the tyre and rusts the rim. Drain the receiver every day, or fit an automatic condensate drain, and install a dryer after the compressor. See our article on water in compressed air.
If you fit tyres in volume, for all types of vehicles, see also our page for tyre centres. Describe your workshop in the configurator, or send us your needs with a quote request.
For your trade: Compressor for truck workshops.