MIRA (Motor Industry Research Association) and RoadSafe welcomed both journalists and ‘opinion formers,’ including representatives from the AA, police and RoSPA, to the association’s test grounds in Nuneaton last month, to host comparative tyre tread depth tests and to promote the industry’s 3mm tyre replacement cause.
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“The UK aftermarket industry must play a key role in bringing the findings of new research into tyre performance to motorists’ attention” – this was RoadSafe’s message at its recent ‘safety in the wet demonstration,’ a message it successfully managed to impress on guests.
MIRA (Motor Industry Research Association) and RoadSafe welcomed both journalists and ‘opinion formers,’ including representatives from the AA, police and RoSPA, to the association’s test grounds in Nuneaton last month, to host comparative tyre tread depth tests and to promote the industry’s 3mm tyre replacement cause.
Guests were offered the opportunity to take part in a practical demonstration that aimed to further impact the tyre safety message. Four cars, each with one of the specified tread depths, 8mm, 4mm, 3mm or 1.6mm were available for guests to complete wet braking tests. The results were strikingly clear, the lower the tread depth the longer and further it took to stop the vehicle. A simple exercise, a simple message; yet despite the simplicity a large percentage of motorists drive on illegal levels of tyre tread. What the 3mm working group says is that it’s up to the UK tyre industry to do something about this and promote change.
There has been a long standing belief that tyre performance in wet weather deteriorates more rapidly as the tread diminishes. But until the BRMA commissioned the first round of MIRA tests last year this belief was merely speculation based on data collected some 20-30 years ago. Part of the problem is that tyre tread depth is a neglected and poorly understood subject in the public domain. Because 95 per cent of road accidents are due to human error the road safety message has traditionally focused on the competence of the driver and not on related issues such as the tyres.
The stopping distance and cornering performance of four sets of tyres with differing treads were measured as part of the BRMA’s original research into the issue. The statistics showed that increases in stopping distances began to manifest at tread depths below 3.5mm. But the industry called for more independent research, and so Continental stepped up and commissioned more extensive tests to ensure that the data was valid for a variety of cars and tyre sizes. It was previously felt that data from just one car was not representative of the UK vehicle parc and did not provide sufficient data for the Department for Transport. The recent MIRA event was then organised to re-affirm that, despite technological advances in vehicle braking, suspension systems or tyre technology over the years, the findings are still the same.
MIRA’s research was carried out on four separate vehicles, a mid range family hatchback, an MPV, executive saloon and a high performance saloon car, measuring stopping distances at 50 mph in conditions that represented moderately heavy rain (0.5mm to 1.5mm water depth). The research discovered that tyres with a 3mm tread had a 25 per cent better performance than those at 1.6mm. In terms of stopping distance this represents an extra eight metres (25ft) in wet conditions. In one test, when a tyre with a tread depth of 8mm was compared to one with only 1.6mm, the stopping distance increased by 13 metres (42.25ft) – the equivalent to double the length of a typical living room. A proprietary premium brand, in a popular tyre size (195/65 R 15), was used in the first test and a further three sizes in the second with different vehicles.
“No one is suggesting that 1.6 mm tyre tread depth is not safe,” commented Adrian Walsh of RoadSafe. “However with 300,000 road accidents taking place every year and a climate which is now much more susceptible to heavy rain, particularly in the summer months, there is need to take action now. If motorists replaced their tyres sooner stopping distances would improve, accidents reduce and lives would be saved. With over 3,500 road deaths a year, what bigger incentive can there be to replace tyres more frequently.”
The campaign is unlikely to provoke a change in the law, even though RoadSafe believes one is well over due. What’s more it is believed that the tyre industry originally advocated a 2mm minimum depth. Vehicle performance has significantly changed since the introduction of the 1.6mm regulation and tyres are generally 25 to 30mm wider today than 30 years ago. The wider the tyre, the more importance is placed on the tread depth, so maybe a review of the current law is overdue, but that is not the group’s primary concern.
Both the companies and safety bodies heading the campaign are calling on garages, retailers and distributors to get this safety message across to the motorist and encourage them to change their tyres earlier. Point of sale literature featuring the campaign’s distinct 3mm logo has already been distributed across the UK to companies involved in the campaign. Major distributors and tyre retailers are displaying ‘tread safely in the wet’ posters and leaflets with the headline, ‘Don’t chance it. Check your tread,’ to help drive the message home throughout the summer. Further attention will be drawn to the group’s efforts in the Autumn when a short video illustrating the tests will be released for use at participating depots. Plans are also well advanced for the launch of a nationwide Tyre Safety Awareness week in October, according to the NTDA, which will include radio interviews with campaign sponsor RoadSafe and a further media campaign, embracing regional and national motoring correspondents.
Continental UK’s general manager of technical services, and technical adviser to RoadSafe, Roger Sanders, believes it will take a year to see a measurable difference, and those involved are well aware that the campaign has got a long way to go to convince drivers to change their habits. First and foremost the industry has to overcome the economic argument that it is simply trying to sell more tyres.
“Whilst it cannot be denied if drivers adopt a removal depth of 3mm, it is likely to lead to increased tyre sales, this is not our motive, it is more a duty of care,” said Continental’s Tim Bailey, a member of the campaign working group, answering the economic question. “These test results clearly indicate a significant drop off in performance at tread depths below 3.5mm and as we believe in the interests of increasing road safety, all drivers should be made aware of this. The decision when to replace tyres still rests with the vehicle owner. It should also be noted that many drivers may already replace tyres before they reach the legal 1.6mm minimum, and we know that major car manufacturers also recommend 3mm. This is also an industry standard in France as shown in their ‘White Book’.”
Mr Bailey is right several car manufacturers do already specify in their owner manuals that tyre performance and safety margins decrease once the tread depth reaches 3mm, owing to a reduction in grip and an increased rise of aquaplaning.
The campaign appears to have industry wide backing, but how effective does it think the industry is going to be in getting the message across to the public? “We are confident that every major retailer wants to use the recommendation, and to display the POS material that has been developed,” said Mr Bailey. “We must accept that it will be a long time until everyone is aware of the industry recommendation as there is little interest in tyres from the majority of the general public, and the majority are not aware of the current limit on tread depth. It will be a long term campaign gradually building awareness in all areas.”
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