Tyre pressure, handling and braking

Brakes stop the wheel; the tyre stops the car. A under-inflated front on a wet roundabout lengthens the ABS chatter and the distance to the Give Way line. The pedal feels the same. The patch does not.

Over-inflation sharpens initial turn-in and then lets go suddenly because the patch is a skinny rib. That is why a “nicely pumped” 3.0 bar Fiesta can feel nervous on broken B-roads.

Electronic stability control assumes a designed radius. A 4 psi-low rear on a rear-drive car can look like a slide the computer then fights. Inflate before you blame the sensors.

Emergency lane changes on the motorway need both axles in the printed band. Fancy summer tyres at the wrong bar are still the wrong bar.

If the car has started to wander at 60 mph and the tracking is recently done, check pressure before you book another alignment. It is the cheaper experiment.