A Hadley Wood van. Not a national brand.

Optimus Mobile Tyres is a van, a rack of the sizes that go on most cars around here, a wheel balancer and a torque wrench, working out of Hadley Wood, Barnet in EN4. There is no bay, no waiting room and no second address.

It is built that way because a tyre is one of the few things on a car that can be changed properly in a parking space, without a ramp, in about the time it takes to drink a coffee. So the kit travels instead of the driver: a gravel drive off Camlet Way, a loading bay on an Enfield estate, the hard shoulder between junctions 23 and 24 of the M25 with the wheels turned away from the traffic.

The work is a replacement tyre, a puncture repaired when the injury is inside the British Standard limits, a locking nut with the key long gone, a run-flat, a van size with the right load index, a battery tested rather than assumed, and recovery for a vehicle that is not going anywhere on its own wheels.

The ground is written down rather than claimed. Fifty-one district codes, one page each, listing every place inside and the main road nearest to it — out of EN4 through Barnet and Enfield, up the A1(M) to Hatfield and Welwyn Garden City, along the A10 to Hertford and Buntingford, and south into Haringey and Islington. It is all on the service area page. A street that is not on one of those pages gets a no, on the call, rather than a van that never turns up.

You will not find an arrival time in minutes anywhere on this site. The M25 decides that, not the person holding the phone. What you do get before anything moves is the figure for the job.

Round the clock. Ring 020 4634 0997 or write to help@optimusmobiletyres.co.uk.