ONE IN SIX SECONDHAND CARS SOLD WITH 'POTENTIALLY DANGEROUS' TYRES - AS EXPERTS CALL FOR RETHINK ON CAR SALES LAWS

One in Six Secondhand Cars Sold With ‘Potentially Dangerous’ Tyres - as Experts Call For Rethink On Car Sales Laws

23 October 2025

• An investigation by Halfords and Cardiff University’s Automotive Department estimates 1.2m cars - around 1 in 6 - are sold each year with potentially dangerous tyres that may not last until their next MOT
• Around 1 in 12 are sold with less than 3mm and would receive a ‘warning’ at an MOT
• Several cars were found to be at or below the legal limit of 1.6mm - meaning they are illegal or could be by the time the new owner gets home
• Cars with 1.6mm of tread take 75 meters further to brake from 70mph vs new tyres
• HALF of Brits who purchased a secondhand car in the past year say they have already had to change at least one tyre
• Currently it is legal to sell cars with tyres at the legal limit of 1.6mm with a 12 month MOT - something experts believe needs to be changed to protect motorists' safety

A new investigation of secondhand car sales has found that around one in six vehicles (16%) being offered for sale in the UK have ‘potentially dangerous’ tyres that may not last until their next MOT.

It also found around 8% are being sold with tyres that would actually receive a ‘warning’ for their condition during an MOT. And many are being sold at or below the legal limit of 1.6mm - including from dealerships. 

The research - commissioned by Halfords and carried out in conjunction with Professor Peter Wells, Director of the Centre for Automotive Research at Cardiff University - investigated almost 500 cars being sold in over 100 locations across the UK. 

The findings - being released during Tyre Safety Month - found that around one in six vehicles (16%) were being sold with 3.6mm of tyre tread or less. 

This amount was considered ‘potentially dangerous’ by Professor Wells as cars on average use 2mm of tread over the course of a year - the next time many will receive an MOT and have them checked. Tyre performance also begins to deteriorate by this stage. New tyres typically come with 8mm of tread. 

Many vehicles were found to have far lower levels. Around 1 in 12 (8%) had 3mm of tread or less - the level which would lead to cars receiving a ‘warning‘ at an MOT if tested in the condition they were being sold. It is also the point where performance noticeably deteriorates (by approximately 20% in wet conditions), meaning they are strongly recommended to be changed.

Four vehicles out of the 481 in the study were found to have tyres at 1.6mm or less. Of them, three had more than 10 months left on their MOT, meaning they would almost certainly be illegal by then. 

Despite technically being legal, tyres with 1.6mm of tread are seriously compromised - they will take 171 meters to halt a vehicle from 70mph in wet conditions, versus 94 meters for the same vehicle with new tyres.  This is the difference between stopping in time, or crashing at 46mph.

One £8,000 vehicle in the sample was being offered for sale from a dealership with visibly damaged tyres with 1.55mm of tread and a ten month MOT. Meanwhile a dealership for a major brand was offering a £15,000 car with a 12 month MOT and tyres with just 1.6mm of tread. Both cars were available for a test drive.  

Currently, cars can be legally sold secondhand with a 12 month MOT and just 1.6mm of tread - the road-legal limit - when just 0.01mm of wear would render them illegal. This would take approximately 33 miles - meaning the vehicle could be illegal by the time the new owner gets their vehicle back home. 

Data from Halfords shows that in the last 12 months, over 6,000 vehicles that came in for a service were found to have less than 1.6mm of tread and were therefore illegal. A further 16,500 had between 1.6-2mm. 

Halfords Garages Managing Director Adam Pay believes these current laws need an urgent rethink. He said “The current rules for tread depth on cars sold do not put motorists’ safety first. Most motorists do not check tyres between MOTs and expect a car they have bought will be safe until its next MOT. The fact it is legal to sell a car with a 12 month MOT that, in a matter of miles or days will be illegal, at best lacks common sense and at worse could cost lives. The law needs an urgent rethink.” 

Professor Peter Wells, Director of the Centre for Automotive Research at Cardiff University, who oversaw the research methodology and analysed the data with Halfords, called the findings extremely worrying and ‘an accident waiting to happen’. He estimates that based on the figures, around 1.2m cars are being sold with potentially dangerous tyres each year, while over 75,000 are likely sold with completely illegal ones. 

He said: “Tyres are one of, if not the most safety-critical aspect of a vehicle. Once they approach 3mm, their braking and roadholding ability has already begun deteriorating noticeably and it only gets worse from there. 

“The difference in stopping distance between new tyres and ones with 1.6mm of tread is 75 meters if travelling at 70mph in wet conditions. That’s the difference between stopping in time, or crashing at 46mph. There is a question of whether 1.6mm should be road-legal at all.”

Professor Wells backed Mr Pay’s calls for the limits to be raised: “I would propose that imposing a legal limit of 3.6mm, or even 4mm, would be sensible.” 

Accompanying consumer research amongst motorists shows most Brits agree. More than 8 in 10 (81%) believe it should be a legal requirement that all cars sold secondhand in the UK should have enough tyre tread to reasonably last until their next MOT.

The research also showed that amongst those who have purchased a secondhand vehicle in the past 12 months, over half (53%) say they’ve had to replace a tyre on the vehicle. Asked how they would feel if they purchased a secondhand vehicle which had less than 3mm of tread, 40% say they would feel ‘let down’ and 35% would feel as if they were being ‘put in danger’. 

TyreSafe - the UK’s charity dedicated to raising awareness of tyre safety, which also runs Tyre Safety month, currently taking place this October - welcomed the findings of the research to raise awareness of the issue.

Stuart Lovatt, TyreSafe Chair said “This is the most detailed study we have seen into the state of tyres on vehicles being offered for sale in the UK and suggests that huge numbers are being sold with sub-standard tyres. Our aim is to reduce tyre-related incidents on Britain’s roads and this research highlights how careful consumers have to be when buying a car and the importance of taking personal responsibility for checking your tyres are safe.” 

To help motorists who have just purchased a second hand car and want to ensure its tyres are up to standard, Halfords offers free tyre checks nationwide including the 10-Point Check, free to Halfords Motoring Club members, and the Free Tyre Check as well as a range of tyre tread gauges that motorists can use to check their tyres themselves. Motorists can find out more about tyre safety at halfords.com/tyre-safety.html

 

For further information please contact Halfords@goodrelations.co.uk or 0207 932 3693

Notes to Editors

●      Testing of tread depth was carried out by Motorvise, who carried out tyre checks on 481 vehicles being offered for sale at over 100 dealerships across the UK. A number of cars being offered for private sale were also included.

●      The methodology and data analysis of the survey was overseen by Professor Peter Wells

●      Methodology for any figures contained with the release are available upon request.

●      Research carried out by OnePoll between 30th September and 2 October 2025, amongst 2,000 UK motorists. 

About Halfords

Halfords is the UK's leading provider of motoring and cycling products and services. Customers shop at 404 Halfords stores, 3 Performance Cycling stores (trading as Tredz and Giant), 604 garages (trading as Halfords Autocentres, McConechy's and National) and have access to more than 200 mobile service vans. Customers can also shop at halfords.com and tredz.co.uk for pick up at their local store or direct home delivery, as well as booking garage services online at halfords.com.

 

 

HALFORDS' RESEARCH, IN COLLABORATION WITH CARDIFF UNIVERSITY

Worn Tyres and Used Cars: The Road Safety Challenge

Commissioned by Halfords, in collaboration with Dr Peter Wells, Director of the Automotive Department at Cardiff University. This research highlights the need for the legally recommended tyre tread depth on secondhand cars for sale to be raised in order to protect motorists.

Summary

• The survey showed 15.6% of used cars on sale had tyres with 3.6mm of tread or less
• Equivalent to 1,192,336 used cars on sale each year in this condition
• With average mileages of 6,700 miles[1], car tyres can wear at the rate of 2.0mm per annum.
• For used cars sold with 12 months’ MOT, the tyres would need to have at least 3.6mm of tread to be road legal until the next MOT.
• 55% of drivers would expect the tyres on a just-purchased used car to last until the next MOT
• Only 37% of drivers know the legal limit for tread depth
• At the typical motorway speed of 70mph, the wet weather braking distance required with the legal minimum of 1.6mm is 170.9 metres, compared to just 96 metres for a new tyre with full tread depth.
• Tyres with a tread depth of 3mm have already lost 20% of their wet weather braking efficiency.
• Even allowing for reduced mileage with older used cars[2], 3.0mm of tread is potentially inadequate to last for 12 months and still be road legal.

The Issue

People are buying used cars with tyres that are technically legal but so worn that they will not last to the next MOT, at great potential risk to themselves and to other road users. This research set out to establish the scale of the problem and to see how far used car buyers understood the issues.

The legal limit for tyre tread depth on cars in the UK is 1.6mm across most of the width of the tyre. As tyres wear down from new (tread depth of 8mm) to the minimum legal depth (1.6mm) the braking performance of the tyres in wet weather deteriorates significantly.

The chart shows this information in graphical form to reveal stopping distances at different speeds for tyres with full tread, 3.0mm tread remaining, and 1.6mm tread remaining.

Motorist and road safety organizations such as the RAC, AA and RoSPA recommend tyres be changed when 3.0mm of tread is remaining^[3].

However, the key issue is how quickly the remaining tread on the tyres of used car will last. Tyre wear is dependent upon multiple factors including the type of tyre, the vehicle, the roads, and the driving style. Aggressive driving with a front-wheel drive car over rough road surfaces and with high-speed cornering will result in accelerated tyre wear rates. As a guide, a reasonable estimate is that 3.0mm of tread is good for about 9 months at 600 miles per month before reaching the legal limit of 1.6mm^[4]. In this research 2.0mm of tread wear per annum was taken as the cautionary benchmark given average mileage and the conditions noted above. Braking distance is taken as a proxy for other aspects of tyre performance that deteriorate as tread depth is reduced.

The Research

To investigate the issue of used car sales and tyre tread depths, two phases of research were conducted by an independent organisation. These were, a dealership used car sales survey, and a questionnaire survey of representative consumers.

Dealership used car sales survey

The dealership survey covered all types of used car outlet in the UK, from major franchised dealers and the large independent used car retailers, through to the small and local sellers of used cars. In total, 481 used cars were surveyed.

The survey included details such as the make and model of car, remaining MOT, retail price as advertised, and the condition of the tyres. Sales staff were asked whether tyres with tread less than 3.0mm could be replaced, and under what circumstances or conditions, and then whether the car was available for a test drive. Sales staff were also evaluated on their helpfulness and professionalism.

The key findings from the used car outlet survey were:

●       0.8% on sale with the legal minimum (less than 1.7mm)

●       15.6% on sale with 3.6mm or less

●       14.6% on sale with 3.2mm or less

●       The average tyre tread depth was 5.1mm

●       No cars were advertised for sale with tyres below the legal minimum

●       The average MOT was 7.3 months

●       31.4% of cars on sale were under £6,999.00

 

In all, 15.6% of used cars for sale had 3.6mm tyre tread or less left, meaning that there is a strong possibility they would be illegal within 12 months.

Overall, the used cars on sale were well presented and 76.9% had tyres that when checked had a tread depth of 4.0mm or more. However, there was an alarmingly wide variation in tread depth and in remaining MOT. This resulted in some stand-out cases where consumers would have to be alert to the potential risk:

 

●       A Ford Focus offered at £5,995 with 11 months MOT and 0.2mm tread depth

●       A Ford Puma offered at £14,999 with 12 months MOT and 1.6mm tread

●       A MINI Clubman offered at £10,995 with 10 months’ MOT and only 1.76mm tread

●       A Peugeot 208 offered at £3,995 with 12 months’ MOT and 1.75mm tread

●       A Nissan Juke offered at £2,895 with 10 months’ MOT and 1.63mm tread

 

All but one of the 481 cars on sale were available for a test drive, regardless of tyre tread depth or condition. In several cases the dealership would commit to getting a full MOT on a car once sold. While most dealers said when asked that they would replace tyres with less than 3.0mm tread very few dealers would not commit to a ‘like-for-like’ replacement.

Consumer survey

The purpose of the survey was to establish how far typical consumers knew the legal and advisory requirements for tyre tread depths, and then to determine consumer expectations about tyre longevity and the MOT when purchasing a used car. A random sample of 2000 consumers was comprised of those considering the purchase of a used car. The results of the consumer survey clearly show:

●       Only 37% of those surveyed knew the legal limit of tread depth

●       More than half (55%) would buy a used car in the expectation that the tyre tread depth would remain legal until the next MOT

●       A compelling 81% believed that tyre tread depth should be sufficient to last until the next MOT

●       Over half (57%) thought that tyre tread depth should be more than 3.6mm when purchasing a used car

●       And 75% of those asked would feel let down, upset, angry or that they had been put at risk if they subsequently discovered the tyres had less than 3.0mm tread.

 

The picture that emerges is that consumers have potentially unrealistic expectations over the longevity of the tyres on a used car, were uncertain over the legal minimum requirements, but equally would be shocked if their used car purchase fell short of expectations.

Put simply, consumers are relying upon sales outlets to identify and replace tyres with less than 3.0mm of tread, and not to be ‘sold as seen’.

The scale of the problem

In 2024 in the UK the total number of used car transactions was 7,643,180 with a growth of 5.5% over 2023^[5]. Based on the outcomes of the dealership survey and the volume of used car transactions in 2024 this means that:

●       A total of 1,192,336 cars were on sale with 3.6mm of tread or less, which for the average mileage could easily be illegal within 12 months

●       267,511 cars with less than 2.2mm tread on sale effectively on the verge of being illegal and offering very poor performance in wet weather braking. With average mileages, these cars would have illegal tyres within 6 months if sold in this condition.

●       Some 557,962 cars were on sale with less than 3.0mm of tread, which would attract an ‘advisory’ warning from an MOT test and is the expected minimum standard for e.g. the RAC and RoSPA.

●       One Ford main dealership was selling a £15k car with 1.6mm of tread and a 12-month MOT...available that day for a test drive.

●       About 0.8% of cars were at the legal limit of 1.6mm meaning, they would be illegal within a matter of days or weeks. Extrapolated to the UK market over 2024, this would equate with an astonishing 63,438 cars.

 

There are about 36 million car MOTs per annum in the UK, with an initial failure rate of 28%^[6]. Tyres are responsible for 60% of MOT failures due to dangerous defects. Compared to other components, car tyres are easy to check, so this high failure rate is indicative of a lack of knowledge or understanding of the issue.

 

The safety implications

The key risk here is that there is a cohort of used car buyers that are not especially well-informed about cars in an era where self-servicing has become a residual hobby for a few. This cohort is likely to increase with time, resulting in drivers taking ownership of used cars with unjustified assumptions of how well the cars will stop in wet weather and at higher speeds. A large number of cars are reaching their MOT date with tyres that result in test failure. Consumers are not aware that the possession of an MOT certificate is not a guarantee that the vehicle is roadworthy. In short, the research reveals an accident waiting to happen.

With continued austerity and an aging fleet of cars in use, the problem is likely to get worse. While many franchised dealerships and approved used schemes recommend tyres be changed if they have less than 3.0mm tread remaining, even this is not necessarily sufficient to last 12 months at typical average mileages. In any case, 3.0mm tread is a minimum recommendation and already means a significant reduction in wet weather stopping ability.

The high volume of used car transactions shows that there are many opportunities for consumers to buy cars with inadequate (albeit legal) tread. Well over a million cars per annum are likely to be on sale with less than 3.6mm of tread, or sufficient to last 12 months to the next MOT without becoming illegal given average mileages.

A mandatory minimum tread depth of 4.0mm for used car sales would appear to be a sensible precaution, even though it might add to the retail price of the car. This would ensure that consumers could have reasonable confidence of a basic standard of tyre performance after initial purchase.

 

Appendix

Table 1 shows the estimated reduction in wet weather braking performance at different speeds and tread depth. At the typical motorway speed of 70mph, the braking distance required with the legal minimum of 1.6mm is 170.9 metres, compared to just 96 metres for a new tyre with full tread depth.

 

Tyre tread depth and braking distances (wet weather)

 

	Tread depth and % reduction in braking performance
	7.0mm 2%	6.0mm 4%	5.0mm 7%	4.0mm 11%	3.0mm 20%	2.0mm 40%	1.6mm 78%
Speed (mph) / Distance (metres)
20 / 12	12.2	12.4	12.8	13.3	14.4	16.8	21.7
30 /23	23.7	24.0	24.6	25.5	27.6	32.2	41.0
40 / 36	36.7	37.4	38.5	40.0	43.2	50.4	64.0
50 / 53	54.0	55.1	56.7	58.8	63.6	74.2	94.3
60 / 75	76.5	78.0	80.2	83.2	90.0	115.0	113.5
70 / 96	97.9	99.8	102.7	106.6	115.2	134.4	170.9

 

(Note: Standard braking distance in wet weather taken from the UK Highway Code)

 

The most popular used car models in the UK in 2024 were:

 

Ford Fiesta	306,207
Vauxhall Corsa	252,761
Volkswagen Golf	231,440
Ford Focus	228,220
MINI	160,516
Vauxhall Astra	159,495
BMW 3 Series	158,674
Volkswagen Polo	151,786
Nissan Qashqai	138,810
BMW 1 Series	125,440

 

On average, cars in the UK are getting older. In 2015 the average age was 7 years and 5 months. By the end of 2024 it was 9 years and 10 months^[7]. Typically, a car is sold three or four times during its useful life. With new car sales well below the pre-COVID peak in 2016 of 2.6 million, more people in the UK are buying used cars, and those cars are being kept longer on the road. More than 40% of cars in use are over 10 years old.

In 2024 there were 35.1 million cars registered in use in the UK^[8]. Used car sales therefore represent about 21.8% of the total vehicles in use in any given year.

Highway Code stopping distances

The Highway Code stopping distances assume that the vehicle, tyres and road are all in good condition. In practice, many variables are potentially important in determining braking distance and overall stopping distance. These variables include: Tyre temperature; Tyre pressure; Tread depth; Tread pattern; Tyre material composition; Tyre profile and design; Tyre damage; Suspension and braking system performance; Vehicle mass and design considerations; Road surface (asphalt; concrete); Road morphology (smooth; ridged, uneven); Road design; and Weather conditions / road surface conditions (dry; dusty; damp; wet; flooded; icy; snowy).

The design of tyres and of vehicle dynamic handling systems has improved greatly over the last twenty years. Recent advances include vehicle stability control and autonomous collision avoidance systems^[9]. These and related developments such as ABS all contribute to improved braking performance. However, tyres are the only point of contact with the road and are crucial to the overall braking and stability performance of the vehicle.

Safety organisations have highlighted concerns with worn tyres and stopping distances. A benchmark study was conducted in 2003 by the test track organisation MIRA on behalf of the British Rubber Manufacturers Association^[10]. According to RoSPA, the study showed that at 50 mph there was a 36.8% increase in total wet weather stopping distance at the legal minimum tread depth (1.6 mm) compared with that prevailing at 3.0 mm tread depth.

New tyre labelling regulations came into force on 1 May 2021, and now include a rating of wet weather grip alongside fuel economy performance. It is important to note that the wet weather grip rating is based on new tyres with full tread depth.