Tyres are responsible for around 1.5% of deaths while driving – around 30 fatalities per year in the UK.
They are likely to be a contributory element in a number of speeding and driving too fast for the conditions factors, which account for 30% of deaths each year – although data in this area is less robust.
Into this scenario comes the European Union’s new tyre labelling regime. While this doesn’t replace the need for a robust tyre management policy, tyre labelling provides insight into three key areas of performance – wet grip, fuel efficiency and noise.
These are the three key performance areas every tyre manufactured from July 1, and on sale from November 1, 2012, will have measured and displayed on a label.
It’s important for fleets to understand that certain performance characteristics are in direct conflict with others.
For example, there is a strong trade-off between wet grip, which requires more rubber friction on the road, and fuel efficiency, which is dependent on lower rolling resistance.
The energy required by tyres to overcome rolling resistance, equates to around 20% of a vehicle’s fuel consumption.
Put another way, this means that one full tank of fuel out of five is used by the tyres.
Energy efficiency also concerns the conflict between reducing fuel consumption and increasing tread life.
To maximize mileage, the easiest solution is to add
more rubber to the tread, so it wears longer. However, this increases fuel consumption, because there is more rubber being deformed with each rotation of the wheel.
Meanwhile, a whole host of criteria is measured in tyre tests but not included within the new tyre labelling scheme, including: wear; driving stability; handling; braking in dry conditions; straight line aquaplaning; curved aquaplaning; and handling and cornering grip in wet weather conditions.
“The label doesn’t tell us anything about the mileage potential of tyres, which is a really important factor,” says Gary Guthrie, global head of marketing at Michelin.
“The real challenge is to be able to deliver all of those performances at the same time in one tyre.”
That’s true if a tyre manufacturer is producing a tyre which prioritises all factors, but not if it focuses solely on the labelling requirement of fuel efficiency, wet grip and noise.
Indeed, a tyre chosen because of high scores in these areas might under-perform in some of the un-labelled – yet equally important – criteria.
Consider the research from Dresden University of Technology in Germany.
It analysed some 20,000 road accidents over a 10-year period and found that 70% of accidents occur on dry roads, which isn’t a test that is included in the tyre labelling scheme.