What is it?

The RAC 635 is one of a series of air compressors from Ring. It boasts a digital readout for choosing a preset air pressure, plus an automatic cut-off that stops when the desired pressure is reached. It connects to a 12v accessory socket and can inflate a flat tyre to 35psi in around three minutes.

Does it work?

The unit is small enough to keep inside the car and comes with the 12v connector, wiring and air hose neatly tucked away inside – then it all packs neatly into a storage case. The whole thing is very intuitive to use - simply hook the air hose up, plug in to the 12v outlet in the car, select the correct pressure for your tyre and press the button.

Once the tyre has reached the pre-selected pressure the system switches itself off and can be disconnected. Easy. If you need to use the compressor at night then it’s fitted with a torch, plus there is a flashing red light for signalling in an emergency and a valve for letting air out of a tyre, if needed.

The display can be set to BAR, PSI and kPa.

There are a few extra attachments to allow the inflation of bicycle tyres, footballs or inflatables like dinghies or air beds. So if you’re outdoorsy then it’s a worthwhile thing to keep in the car even if you’re not too worried about your tyres. Build quality is sturdy - in our testing we dropped and bashed the unit and while it does have a few little scratches here and there it’s still in one very chunky piece.

Prices vary depending on where you buy, but typically the RAC 635 can be found for around £30. At that price it’s a smart buy, particularly if you have a second car that rarely moves and needs its air topping up before a drive, or if you have an outdoor hobby like cycling, camping or water sports.

Price: around £30
Key features: Air pressure selection. Automatic cut off.   
Alternatives: Michelin High-Power Tyre Inflator - around £35