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Tyre under-inflation – the facts

Tyre pressures have a direct impact on a vehicle’s fuel economy, with under-inflation increasing both fuel usage and carbon emissions, whilst also posing serious safety risks to motorists and other road users.

  • Over 12 months there were 61,405 UK commercial vehicle breakdowns. The cost to UK Plc was £136,000 per breakdown, and approaching £1.5 m for a three lane motorway closure lasting up to 4 hours. (Highways England 2016)
  • In this same period there were 32 deaths and 1,500 serious injuries due to defective tyres. (Highways England 2016)


“According to a recent roadworthiness report commissioned by Highways England and published in 2016, more than 85,000 breakdowns on the UK roads take place every year due to poor vehicle roadworthiness. The report found that almost a third of accidents in which vehicle defects were a contributory factor were due to underinflated, defective or illegal tyres. Studies from different tyre manufacturers show that more than 50% of all passenger cars are driven with underinflated tyres and tests with underinflated tyres show an increase in the risk of adverse safety consequences in emergency situations. Campaigns to increase awareness of the importance of checking tyres could help to reduce vehicle breakdowns and crashes.”

Dr Lisa Dorn PhD; C.Psychol; AFBPsS; MIEHF; FHEA
Associate Professor of Driver Behaviour
Cranfield University


Opportunities to save
The impacts of under-inflation
Focus on fleet savings
Safety first

Jonathan Layton, Michelin’s National Sales Manager for Services & Solutions, said: “Driving on tyres just a few psi below the manufacturer’s recommended pressures will reduce a vehicle’s fuel efficiency on every single journey. And when fuel costs rise, the impact of this under-inflation pushes running costs higher.

“A lot of fleet drivers routinely monitor their average fuel consumption via the dashboard display, and many will even be aware of small differences between journeys. Just imagine how much UK businesses could save if drivers paid as close attention to their tyre pressures as they did to their mpg readout.

“Maintaining accurate tyre pressures is a small but simple step to improving fuel efficiency, maximising vehicle safety and reducing carbon emissions.”

UK data collected by Michelin in the 10 years ending 2017 shows that, on average, at least 60 per cent of motorists drive on under-inflated tyres, and half of those are at dangerously under-inflated levels (more than 8psi).

As well as increasing fuel bills, under-inflation makes a vehicle’s steering less precise, increases stopping distances and leads to a higher risk of aquaplaning. It also reduces a tyre’s endurance capabilities, making it more prone to damage and possible rapid deflation.

During 2017 national tyre expert ATS Euromaster surveyed the pressures on more than 1,000 cars across 28 of its centres in support of October’s Tyre Safety Month, and 561 had under-inflated tyres – a figure tallying closely with the 57 per cent recorded by industry charity TyreSafe.

In Marlborough, a staggering 91 per cent of cars tested by ATS Euromaster were running on at least one under-inflated tyre – and not a single car checked during the week sported a correctly inflated full set.

Paul Millward, ATS Euromaster’s Health, Safety and Environment Manager, commented: “We know that under-inflated tyres are a huge problem across Britain but we were blown away to discover that in some parts of the country, we didn’t see a single retail or fleet customer running tyres at the correct pressure.

“Under-inflated tyres pose a serious safety hazard, as they increase braking distance, meaning your tyre pressure could be the difference between stopping safely and causing a serious accident.”

Failing to keep your tyres properly inflated needlessly increases fuel bills – multiply that effect across a whole fleet – and it can have a significant impact on the bottom line.

TyreSafe estimates that in the UK, as much as £700 million of fuel a year is wasted because of under-inflated tyres. When tyres run under-inflated, their rolling resistance – the force that is needed to make them turn – increases. This means the engine must work harder and more fuel is used, making the vehicle less economical.

The air pressure within a set of tyres is the number one factor which determines how well they perform. A tyre’s pressure affects load carrying capacity, speed capability, handling response, wear rate and overall safety. What’s more, under-inflated tyres will cause a vehicle car to use more fuel and emit more CO2 emissions.

It’s therefore critical for your safety and comfort that your tyres are properly inflated in line with the vehicle manufacturers’ recommendations. Tyre pressures should be manually checked when they are cold at least once a month or before a long journey.

CALL: +44 (0)1543 415823
Wheely-Safe Ltd,
Ground Floor, 1 Newlands Court
Attwood Road
Burntwood, Staffordshire
WS7 3GF, United Kingdom
Company Registration No. 07184108