Tyre labelling EU legislation changes
From 1st November 2012, the laws are changing with regard to tyre labelling. For once, EU regulations put a positive spin on things with far clearer information and comparable data, finally giving consumers facts and figures they can work with to make an informed choice.
We've been used to the A to G efficiency coloured guides on household white goods for some time now and the same info now comes to tyres.
There are 3 categories that you can now evaluate your new tyres on -
Fuel Efficiency - (determined by rolling resistance) - Graded from A to G where A is the most efficient and G the least (D is skipped for some unknown reason).
Wet Grip - (determined by braking performance on a wet road) - Graded from A to G. A is the shortest braking distance and G is the longest. Just to complicate what's otherwise a clear matter, D & G aren't used!
External Rolling Noise - measured in decibels (DB) and categorised in 3 levels with a symbol showing a 'wave' of noise. Wave 1 is the quieter tyre while 'volume' level 3 is the loudest.
Important facts and figures
Fuel efficiency - the higher the 'rolling resistance' of a tyre, the harder the vehicle has to work to drive the vehicle forward and therefore the engine produces more co2 and uses more fuel. There's a 7.5% loss of economy between the best and worst for a full set of tyres on an average family car. That could be as much as 6 litres for a tank fuel.
Wet grip/braking performance - the ratings are calculated by the distance travelled by car after braking at 50mph in the wet (testing regulation EC1222/2009). There's a 30% gap between the best and worst giving a scary 18 metre or approx 4 car lengths extra stopping distance.
Noise emission/Exterior noise - 1 black bar on the chart is below future EU limit DB limits. 2 bars meet future EU limits while 3 is at least 3DB's below future limits. I think they heard us coming with this one.
How the tests are conducted
Rolling resistance - A passenger car wheel and tyre is mounted in a 2-metre drum and run at a set load and pressure. The drum requires a certain torque to spin when the tyre is not in contact with it. The tyre is then brought into contact with the drum and the additional torque required to spin it is measured. The result is the Rolling Resistance Coefficient in Kg/t
Wet grip - There are 2 methods of testing for wet grip. The first is wet braking performance on a road surface where the vehicle is braked from 80km/h to 20km/h. The second test is carried out on a skid trailer where the friction between the road and the tyre is calculated. This is carried out at 65km/h. The result of both tests gives the 'Wet grip index' (WGI) and describes the percentage improvement in relation to the reference tyre.
Noise emission - The ISO 'pass-by' noise test is conducted by passing a car between two microphones positioned 7.5 metres from the centre line and at a height of 1.2 metres.