How to use a cordless tyre inflator
Updated: 21.10.2026
The sidewall shows a much higher number than the sticker on the driver's door. That sidewall figure is a maximum, not the pressure your car should run. This is how to use a cordless tyre inflator so you set the placard's cold number, in the placard's unit, and stop if the tyre is damaged. The Products Compared editorial team wrote it on 19 October 2026 from Michelin UK, the Highway Code and the listings in our [cordless compressor comparison](/hub/compressors/cordless-compressor). It is not a lab procedure. A qualifying purchase can earn a commission at no extra cost to you. Button names differ by model. The order does not.
The sidewall shows a much higher number than the sticker on the driver's door. That sidewall figure is a maximum, not the pressure your car should run.
The sidewall shows a much higher number than the sticker on the driver's door. That sidewall figure is a maximum, not the pressure your car should run. This is how to use a cordless tyre inflator so you set the placard's cold number, in the placard's unit, and stop if the tyre is damaged. The Products Compared editorial team wrote it on 19 October 2026 from Michelin UK, the Highway Code and the listings in our cordless compressor comparison. It is not a lab procedure. A qualifying purchase can earn a commission at no extra cost to you. Button names differ by model. The order does not.
Our top picks
| Badge | Product | Hose | Auto shut-off | Power | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Lamicall Lamicall VHEP02 | 30 cm | Yes | Built-in 6000 mAh | 9.1 | about £42.99 | View offer |
| Best value |  HOVVIDA HOVVIDA AM21J2 | 8 inches | Yes | Built-in 5200 mAh | 8.4 | about £24.99 | View offer |
| Alternative |  ASNUG ASNUG H22 | 17 cm | Yes, in reviews | 3600 mAh plus 12 V | 6.5 | about £19.99 | View offer |
On this page
Read the placard, not the sidewall
Open the driver's door, or the fuel flap, and read the line for the axle you are filling. Front and rear often differ, and a loaded car can have a second pair of figures. Highway Code Annex 6 says to check weekly, on cold tyres, against the manufacturer's pressures. A car mode on the HOVVIDA, Lamicall, Tarden or Motorenbau is a generic band, not your car. Change the stored number until it matches the sticker. Michelin UK is clear that the sidewall maximum is not the daily pressure. If the sticker is missing, use the handbook for that model and load. The cordless tyre inflator for car page covers the warning lamp.
Cold, warm, and the unit on the screen
Michelin says to measure after about two hours standing, or after a short hop under about two miles. If you must add air to a warm tyre, add 0.3 bar to the placard, about 4.35 PSI. Do not let air out of a warm tyre to chase the cold number. The pressure falls as the tyre cools.
Set the unit before the number. These pumps offer PSI, bar, and often kPa. The Motor Ombudsman notes that bar times 14.504 is PSI. If the screen is on PSI and you enter 2.4, the tyre will be almost empty. If it is on bar and you enter 36, you are asking for a pressure far above the sticker. Several inflators remember the last unit, so look again after a bike session.
Connect, including a bike valve
Screw the chuck on until it seals, and support the body. The HOVVIDA hose is 8 inches, the ASNUG hose is 17 cm, and both Lamicall hoses are 30 cm. Left alone, the pump hangs on the valve, the seal leaks, and the reading jumps. The NOCO page says 10 inches in one field and 3 feet in a bullet, while reviews describe a short tube. Hold that one too.
Most car valves are Schrader. A road bike is often Presta. Unscrew the small Presta nut before you fit the adapter in the box, and do not force a Schrader chuck into a Presta rim. Balls use the needle, at the pressure printed on the ball. The HOVVIDA listing excludes air mattresses, paddleboards and large truck tyres, and it suggests a cool-down after 15 minutes. A football and a paddleboard are not the same volume.
Stay with it, then stop
Auto shut-off stops at the number you stored. Stay until the motor cuts, then read the screen. A leaking chuck can show the target while the tyre is still short. The HOVVIDA will not start while the charger is plugged in, so unplug USB-C first. On the ASNUG, one reviewer says the 12 V lead runs the pump and does not charge the pack. Charge a pack that has sat in the boot before you rely on it.
Stop if you see a bulge, a split or cord, or if the pressure falls straight back after the pump stops. In live traffic, call breakdown cover rather than kneeling at the wheel. Refit the valve cap. The cordless compressor buying guide is where you choose the pump. A 6 litre Einhell has no tyre preset.
Common questions
Where is the right pressure?
On the placard in the driver's door or fuel flap, for that axle and load, or in the handbook if the sticker is gone. Highway Code Annex 6 points at the manufacturer's cold figure. The sidewall number is a maximum. A car mode in the menu is a generic preset. Change it until the screen matches the sticker, in the sticker's unit.
What if the tyres are warm?
Michelin UK treats a tyre as cold after about two hours, or a short slow hop under about two miles. If you must set it warm, add 0.3 bar, about 4.35 PSI. Do not bleed a hot tyre down to the cold number. The pressure drops as it cools, and you would then be under the placard.
How do I avoid mixing bar and PSI?
Read the unit before you enter the number. Bar times 14.504 is PSI. A sticker at 2.4 bar is not 2.4 PSI, and 36 PSI is not 36 bar. A band near 30 to 36 PSI is only a sense check. These pumps remember the last unit, so a bike session left on PSI will still be on PSI for the car.
How do I fit a Presta valve?
Unscrew the small nut on the stem, fit the adapter from the box, then fit the chuck. Do not push a Schrader connector straight onto Presta. If the screen does not move when the motor starts, the nut is closed or the thread is crossed. Reseat it, and support a short hose so the pump is not hanging on the valve.
Can I walk away once auto shut-off is set?
No. Stay until it cuts, then read the number. A leaking chuck stops at a target the tyre has not reached. The short hoses on the HOVVIDA, ASNUG, Lamicall and NOCO listings all need a hand under the body. Auto shut-off is a convenience, not a second person at the valve.
What if the pump will not start while it is plugged in?
On the HOVVIDA, unplug the charger first. The listing says it cannot run while charging. On the ASNUG, one reviewer says the 12 V lead does not charge the internal pack, so that lead is not a full battery. If the pack has sat in the car for weeks, charge it from USB at home before you rely on it.
When do I stop and call someone?
Stop if the sidewall is bulging, cord is showing, or the tyre will not hold what you just added. That is a fitter's job. Stop if you would be working in live traffic, and call breakdown cover. A lamp that stays on after a correct cold fill can be a sensor fault. The car page covers that lamp. This sequence ends when the reading matches the placard, or when the tyre is unsafe to keep filling.
Related pages
Sources
Public UK sources and the manufacturer page below. amazon.co.uk listings checked on 19 October 2026.
- Highway Code Annex 6: vehicle maintenance, safety and security (retrieved 19 October 2026)
- Construction and Use Regulations 1986, regulation 27 (retrieved 19 October 2026)
- MOT inspection manual, section 5: axles, wheels, tyres and suspension (retrieved 19 October 2026)
- HSE INDG178: written schemes of examination (retrieved 19 October 2026)
- HSE: Pressure Systems Safety Regulations overview (retrieved 19 October 2026)
- Control of Noise at Work Regulations 2005, regulation 4 (retrieved 19 October 2026)
- Einhell UK: TE-AC 36/150 Li OF-Solo (retrieved 19 October 2026)
- Michelin UK: how to inflate your tyres (retrieved 19 October 2026)