Added: 07 February 2018

Almost 40% of cars could be running on at least one tyre that is ‘dangerously’ or ‘very dangerously’ under-inflated.

The estimate comes from an inspection organised by Michelin of more than 500 vehicles in Tesco car parks around the UK.  It found that 28% of cars had at least one dangerous tyre, and a further 12% had at least one very dangerous tyre.

Michelin classifies tyres that are between 7psi and 14psi below the manufacturer’s recommendation as ‘dangerously under-inflated’, while 14 psi or more under-inflation is deemed to be ‘very dangerous’.

“Driving around on under-inflated tyres costs money and can also cost lives,” Jamie McWhir, Technical Manager for Michelin in the UK, said.  He added that checking tyre pressures regularly “makes sense from a cost and environmental point of view, but more importantly it’s critical for the safety of the vehicle, its passengers, other road users and pedestrians.”

Running a car with tyres under-inflated by 7psi decreases fuel efficiency by about one mile per gallon, according to Michelin.