What’s the difference between driving on tyres with 1.6mm tread and scrolling on your phone behind the wheel? The first these is entirely legal, but as the team at Halfords points out, just because something is allowed doesn’t mean we should do it. In fact, a study it commissioned indicates that tyres worn to the current legal UK limit have a greater influence on stopping distance than driver phone use. Based on this result, Halfords opines that the UK minimum tread depth may be too low.
Commissioned by Halfords and conducted by the Director of the Centre for Automotive Industry Research at Cardiff University in February 2026, the study found that on average, phone usage increases reaction times for braking by 0.5 seconds. At 70mph, this will increase stopping distance by an additional 15.55 metres on wet road surfaces. However, if the car has tyres with just 1.6mm of tread, stopping distance will be 27 metres longer – an additional six car lengths – than a car with tyres in good condition.
This means that a car travelling at 70mph, with good tyres will take 96 metres to stop in the wet. If the driver of this car is using a phone, stopping distance will increase on average to 111.5 metres. But even if the driver has the sense not to use their mobile when behind the wheel, stopping distance would increase to 123 metres should the car wear tyres worn to 1.6mm.
Tyres a greater factor at higher speeds
To demonstrate this, Halfords has created a video showing the difference in stopping distances. The film shows the effects of both worn tyres and mobile phones use versus a vehicle with tyres in good condition.
The research found similar increases in stopping distance between worn tyres and mobile usage in speeds up to 40mph. However, above this, tyres were found to increase stopping distance more than phone usage.
Government data shows an increase in the number of deaths or serious injuries on our roads as a result of dangerous tyres – rising from 147 in 2022 to 172 in 2024 (the most recent data available).
Halfords says it has released these findings to encourage a change in the current attitudes towards the dangers of worn tyres – it shares that just seven per cent of drivers believe worn tyres can be more dangerous than using a phone at the wheel. When informed that tyres with just 1.6mm of tread do more to increase average stopping distance at speeds above 40mph than driver mobile phone use, 53 per cent of respondents expressed surprise.
“The findings are being used to demonstrate the current rules on tyre tread may need to be reviewed with a greater focus on enforcement (similar to mobile distraction) so motorists pay more attention to the safety of their tyres,” states Halfords. “Professor Wells and Halfords recommend that drivers change tyres once they get to around 3mm of tread.”
Support for tougher penalties
In addition to commissioning the study, Halfords tasked One Poll with contacting a sample group of UK motorists to gain a better understanding of tyre- and phone-related driving awareness. Between 5-9 March 2026, One Poll spoke with 2,000 people, and found that 31 per cent of respondents believe that the current limits on worn tyres should be raised, with 53 per cent saying that driving with worn tyres should be penalised with tougher penalties.
It also highlighted a wider lack of knowledge when it comes to tyre safety. Just 28 per cent of motorists are aware that the current legal limit for tread depth is 1.6mm. More than four in ten guessed incorrectly, while 29 per cent didn’t know the correct measurement at all. In addition, 28 per cent said they are not confident they would recognise when their own tyres needed replacing, with ten per cent admitting that tyre tread and pressure is only checked when their car goes in for servicing, while 30 per cent check this just ‘a few times a year’.
Legal minimum not a safety benchmark
“The impacts of phone usage and worn tyres have never been compared before and the study suggests that purely from a stopping distance perspective, the impact of worn tyres is generally worse,” states Professor Peter Wells, Director of the Centre for Automotive Industry Research at Cardiff University. “Of course, the impact of phone usage will be variable, but the findings offer a strong guideline as to the dangers. Drivers need to be aware that tyre performance begins to become impaired long before they reach the legal limit.”
Adam Pay, Managing Director of Autocentres and Mobile Network of Halfords, says: “Most drivers know using a phone behind the wheel is dangerous. What this research shows is that tyres worn down to the current legal limit can actually have an even greater impact on stopping distance. The legal minimum shouldn’t be mistaken for a safety benchmark. When tyres reach that point their performance is already significantly reduced, which raises an important question about whether the current limit is where it should be.”
Stuart Lovatt, TyreSafe Chair adds: “This study highlights a critical and often overlooked factor in road safety: the physical relationship between tread depth and stopping distances. While the UK legal limit remains 1.6mm, the data shows that at motorway speeds, the impact of worn tyres on braking can be even more significant than driver distraction. We encourage all motorists to treat tyre maintenance with the same seriousness as they do mobile phone use. Whether a driver chooses to replace their tyres at the 3mm mark recommended by some experts or waits until the legal limit, the priority must be regular safety checks. As tyre technology evolves to meet new wet-braking standards, staying informed about your vehicle’s actual performance is the best way to keep our roads safe.”
Phones an ongoing danger
Halfords is also using the research to highlight to motorists the ongoing dangers phones present. Two-fifths of drivers reveal that they make or receive calls while driving and 39 per cent say they use their mobile phone for playing music while they drive. And 54 per cent admit having to rely on using satnav on their phone when they drive, meaning the phone is always nearby.
Free tyre checks
Halfords invites motorists who want to check on their tyres and save on the cost of their next MOT to sign up to Halfords Motoring Club for free at www.halfords.com/motoring-club where they will receive a £5 voucher as well as a £5 discount off their MOT, plus a free ten-point car safety check worth £15. Drivers can also get a free tyre check any time at any Halfords or National Tyres and Autocare garage.
