It is estimated that this is costing British motorists £2.2 million on wasted fuel every day.
Regular tyre checks are more important in the winter, when temperatures can fluctuate considerably, leading to a fall in tyre pressure.
The average tyre loses roughly 1psi of pressure for every 10 degree drop in temperature.
Studies by Cooper Tire Europe found that just 5% of vehicles are running on correctly inflated tyres.
The remaining 95% are risking not only increasing their stopping distances in an emergency, but also raising their fuel consumption by at least 2.5%.
Checks found that the average car tyre was already under-inflated by 10% of the manufacturer’s recommended pressure.