Fleet News

Fleet Insight: Tyre row brews over minimum tread depth

Fuel efficiency, safety and noise are the three areas where the battle for tyre supremacy is fought. New products jostle to highlight ever improving fuel consumption and shorter stopping distances – both of interest to fleets.

However, clear lines have recently been drawn over the issue of minimum tread depth with major disagreements between three of the dominant brands in the UK market, Continental, Michelin and Goodyear Dunlop.

Continental Tyre, an original equipment supplier to more than 30% of all new European cars, is campaigning for a new minimum limit of 3mm – currently 1.6mm in the UK – which it claims would result in a significant cut in traffic accidents.

But its bid to change the law is being challenged by rivals Michelin and Goodyear Dunlop.
“We are not in favour for two reasons. The first relates to environmental and cost reasons – if everyone had to change their tyres at 3mm, we would have to manufacture more tyres and dispose of more tyres,’ says Michelin spokesman Peter Snelling.

“Our second reason is that there is nothing to say that moving to 3mm from 1.6mm has any impact on safety. There is absolutely no data to show more accidents occur as a result of people having tyres at the current minimum tread depth.

“What we are keen to make sure happens is that people adhere to the law. We know that many go beyond the 1.6mm limit and this is dangerous – there are statistics to prove that once you get down to 1mm tread depth and less, braking distances are much greater, particularly in the wet.”

A Goodyear Dunlop survey found that four of every 10 tyres removed from cars at its centres were illegal.

“It is a matter of concern that they have been driven into the depots in that state, so if we are to get an improvement in road safety, we really need to push for rigorous enforcement of the law,” says spokesman James Bailey.

“If the minimum depth were to be changed to 3mm, we would all sell more tyres, but we believe this would add to fleet costs by forcing operators to throw away tyres that still have a good level of tread.”

According to Bailey, recent advances in technology allow the latest Goodyear tyres to retain the same wet weather performance throughout their life.

“Performance in the wet no longer declines in a linear way with the tread depth. We’re now able to run on a harder compound tread when the tyre is new and enter a softer compound after 15,000 miles to offer the same levels of grip and adhesion,” he says.

“In addition, the smart wear technology in our latest OptiGrip covers allows new tread patterns to appear after 15,000 miles to allow the tyres to evacuate the same level of water as they do when new.”

Goodyear tyre technology director Jean-Pierre Jeusette adds: “It is easy to develop a tyre that provides a lot of mileage, but our focus is on developing covers that have excellent performance in safety-related areas like braking and handling, particularly.

“Smartwear allows us to provide this over the lifetime of the cover, without having to compromise on mileage or other important parameters. This is a major step forward and is our main reason for saying there is no need for an increase in minimum tread depth.”

However Continental maintains that its studies and those of independent exp-erts have shown that braking distances, particularly in the wet are greatly increased after the tread depth falls below 3mm.

Its spokesman says: “The 1.6mm legal limit dates back to 1992 when cars had thinner tyres and less horsepower. Over the years, the trend on new cars has been to have larger, wider tyres with lower profiles to improve performance and styling.

“This means that the contact patch on the road is larger, which is great for braking in dry weather, but a problem when conditions are wet. The greater contact patch means you are at greater risk of aquaplaning and a tread depth of 1.6mm is not sufficient to channel the water away from under the tyre, mean-ing it loses contact with the road and the driver can lose control.

“Although many cars come with ABS and ESC to help the driver keep control, these have little benefit if the tyres are not in contact with the road. Research shows the risk of aquaplaning becomes more pronounced when the tread depth goes below 3mm.”

Tests carried out by Auto Express at MIRA in 2006 using four different vehicles showed that with maximum brake force applied at 70mph on an asphalt surface covered with up to 1.5mm of water, it took 104.7 metres to stop on tyres with 3mm tread depth and 142 metres to stop on tyres at 1.6mm.

Labelling will help tyre selection

Tyres are set to join white goods items like fridges and washing machines in carrying Government labels to rate their performance.

New regulations will require descriptions aimed at helping drivers reach a more informed decision about their suitability for a particular vehicle.

For the first time, key information on rolling resistance, noise and minimum safety standards will be rated between A for best and G for worst on labels that will make it easy to identify performance.

The Government is expected to make it obligatory for tyre dealers to adopt a standard format to explain differences when the labelling law comes into effect on November 1, 2012. Re-treaded tyres, off-road professional tyres and racing tyres will not be included in the scheme.

“We welcome this move. Maximum levels of rolling resistance and noise will be imposed as well as minimum levels of wet grip. It should make tyre purchase as simple as buying a new fridge,” says Michelin spokesman Peter Snelling.

“We produce greener tyres and will never compromise on safety and believe the use of innovative technologies is the only way to optimise the key tyre characteristics at the same time.”

Goodyear Dunlop spokesman James Bailey agrees: “The aim of this new legislation is to influence consumers to buy more energy efficient and safer tyres. As they are the only contact area with the road surface, tyres play a key role in braking performance and their rolling resistance directly impacts fuel consumption and emissions.

“Having a labelling system is going to be a great help and will also drive home the point that you only get the level of performance that you pay for.”

Kwik-Fit Fleet head Mike Wise warned that increased focus on cost management could prompt some operators to select lower-performance replacements.

“Safety should be the top priority and fleets should also remember that premium covers are likely to return improved economy as well as having a longer service life,” he says.

Tyre technology plays increasing role in improving fuel efficiency

Tyres account for almost a fifth of the energy needed to drive a car with an internal combustion engine. For vehicles driven by electricity, the loss rises to 30%, so it’s small wonder that energy-saving technology is playing an increasingly significant role in cutting fuel use.

Over the past 30 years, Michelin claims to have reduced tyre-related fuel consumption by half while improving performance in key areas such as safety and longevity.

The company has pledged to repeat that feat over the next three decades and the fourth generation of its energy saver has already made an impressive start. It is credited with reducing fuel consumption across Europe by around 100 million litres.

In recent comparisons undertaken by the independent testing organisations DEKRA and TÜV SuD, Michelin’s Energy Saver delivered lower rolling resistance, longer life and benchmark wet grip. Cars fitted with it used 2.5% less fuel. How is it done?

“Bend a pencil rubber a few times and it heats up. The same thing happens from the movement and vibrations as the contact patch of a tyre touches the road surface,” product marketing manager Steve Dolby told Fleet News.

“Our object is to develop compounds that heat up less. The key lies in the mix of compounds as well as using the latest generation of silicon and other components.
“The clever use of compounds and the latest materials allows us to achieve both aims at the same time.”

Energy saver’s rival from Goodyear – EfficientGrip – was also tested by the TÜV organisation in Germany.

Compared with average results from four leading premium brand competitors, the new cover was declared to have 13% less rolling resistance, 2% shorter braking distance and 8% higher mileage on driven wheels.

“We put a lot of work into developing a new compound and a new type of tread pattern because we were unwilling to compromise on wet weather grip in any way,” said Goodyear Dunlop spokesman James Bailey. “The key message is that in producing a fuel saving tyre, you don’t have to compromise on safety – and that’s not always been the case in the past.”

Longevity is another key performance area for fleets, according to Dolby. “Longer life means less tyres per contract. We estimate the average life for our covers is 28,000 miles, but this can be considerably more on vehicles in regular motorway use,” he says.

“The fuel-saving benefits are often hard to measure in fleet use because of different driving conditions and different types of journeys. But lower rolling resistance will always generate some level of saving and this is our standard offer – fitting energy-savers adds no additional cost.”

Case study: Hitachi Capital

Replacement tyres represent a major concern for contract hire and leasing companies. "The amount of money they cost is difficult to build into our rates because it is impossible to estimate how long they last," says Hitachi Capital fleet services manager Malcolm Roberts.

But an annual spend of £2.5 million on tyres means replacements are a big issue.

"Tyres represent 30% of the budget we set for maintenance, servicing and replacements, but identifying the cover with the longest service life is a nightmare. We have a lot of data, but a diverse mixture of vehicles and drivers make analysing it difficult, to say the least.

Hitachi decided to place all its tyre business with a single premium brand several years ago.

"We chose Michelin because It is recognised for longevity and has a great track record in energy saving. In addition, it is a strong brand, which is important with drivers. We’d get a lot of adverse feedback if we fitted second grade tyres," Roberts said.

Case study: Chiltern Transport Consortium

Fuel-saving technology coupled with high performance has prompted police forces across five counties to specify Goodyear’s latest tyre for their patrol vehicles.

"No matter what size of fleet you run, fuel costs account for one of the highest areas of expenditure – so fuel saving is at the heart of our efforts to reduce costs," says
Chiltern Transport Consortium head Ian Godophin.

Responsible for overseeing the fleets across 4,500 square miles of Buckinghamshire, Oxfordshire, Bedfordshire, Hertfordshire and Berkshire, the consortium
operates more than 2,300 vehicles.

The vehicles cover annual distances of around 35 million miles and use about £7 million worth of fuel each year.

"We have been impressed with the performance of the Efficient- Grip, which helps deliver fuel savings while also offering high mileage and excellent wet braking performance," says Godolphin.

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  • Pauls - 01/04/2010 14:12

    Surely the restrictions imposed on tyre outlets when changing tyres needs to be concidered. Advice from tyre manufacturers, vehicle manufacturers and road safety groups tells us to always change tyres in pairs, never fit different brands/models of tyre on the same axel, and to rotate our tyres to put the new rubber where it gives most benefit, yet the tyre service providers cannot replace tyres in pairs, nor rotate tyres, meaning in my own case I am soon to have tyres from 3 brands on my car, all at differing levels of wear, and I am left wondering is my vehicle safe or is all the advice not to be believed?!

  • Ian Lisle - 27/02/2014 12:37

    Do the UK government play their part in highlighting the dangers of illegal tyres? There appears to be very little public information on the subject. Current UK tyres laws and the consequences of illegal tyres in my experience the vast majority of motorist do not even know the UK tyre laws, nor are they aware of the penalties an individual can incur, but more importantly the very real dangers that exist to other road users. If successive governments are serious about improving road safety then surely a public awareness campaign would result in fewer fatalities on the UK roads. However this does not appear to be the case as the state of the UKs roads appears to be of little concern to the government as they continue to deteriote at what is now becoming an alarming rate. On a daily basis I travel on roads that are now in such a dangerous state that a fatality is only a matter of time before we see a massive increase in serious RTA. The mentality of many motorist is if the Government, local authorities & Highways Agency show such scant regard for conditions of many major roads and motorways then why should the motorist bother showing any responsibility about their own vehicles tyres? Although a selfish attitude this is how many people think. Lead by example is a phrase that springs to mind, but if both problems continue to be ignored we have a ticking time bomb just waiting to explode. Ignorance is bliss but it will undoubtedly cost lives. We don't really need any surveys or studies to reveal that it is blatantly plain and obvious to see every day that we have a lethal combination of tyres and road surfaces just not fit for purpose. This surely cannot continue but as with most issues it takes a major disaster to occur, which once it becomes headline news and is seen to be politically damaging do the people empowered to ensure everyone's safety actually do anything, which often can be knee jerk reactions and not a solution to an ever deepening crisis. It would be interesting to hear the views of the Minister for Transport, the Head of the Highways Agency and some senior Council Executives, as at the moment all appear to have their heads buried deep in the sand and appear to be oblivious to two serious issues.

  • Ian L - 30/04/2015 10:54

    I am a little surprised that there hasn't been an EU Directive on this issue. Surely there must be stats from other countries who state a minimum tread depth of 3mm. It can also be confusing to motorist as some tyre manufacturers have a 3mm and 1.6mm wear indicators . Any changes would have to be phased in over a period of time as to just state a date that the changes came into force would be totally unmanageable. From a safety prospective I personally think that there are far greater risks from the part worn tyre market, which the demand appears to be increasing which just does not appear to regulated at all. UK minimum tread depths have been set at 1.6mm for as long as anyone can remember. However vehicles and tyre design and manufacture has changed beyond recognition over the same period. Should tyre laws in the UK evolved at the same pace or stand still as appears to be the case. The argument cost over safety has to be a none starter if the facts prove that other EU countries have a lower or higher accident rate.

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