We know that wheel alignment, tyre type and tyre pressure all have a major impact on fuel consumption.

—Arne-Helge Andreassen, business area manager for tires and wheel alignment at Volvo Trucks' Aftermarket department

Since fuel consumption is directly linked to carbon dioxide emissions, Volvo Trucks and tyre manufacture Michelin decided to produce statistical data on just how much wheel alignment, tyre pressure and rolling resistance affect fuel consumption and thus carbon dioxide emissions. In a two-week long test, a rig with optimal tires, tire pressures and wheel alignment was compared with a vehicle featuring different wheel alignments and tyre parameters.

Analysis of the test results reveals that there can be a difference of as much as 14.5% in fuel consumption depending on how the wheels are aligned and equipped. Choice of tyre can cut consumption by as much as 11%, correct tyre inflation brings a reduction of 1%, while proper wheel alignment can cut fuel consumption by 2.5%.

Commercial traffic accounts for 30 to 40 per cent of total carbon dioxide emissions from road transport.

For the test, Mats Lidbeck from SP (the Technical Research Institute of Sweden) was on location both at the test track and in the workshop when the tests were carried out. SP served as a guaranteed neutral third party and reviewed the measurement methods, ensuring that the engineers had taken into account all the most important aspects.

The tests used two Volvo FH 4x2 trucks, each equipped with a 500 hp 13-liter Euro 5 engine, and each hauling a fully loaded van-bodied trailer. The rigs each weighed 40 tonnes gross. One rig was driven with a variety of incorrect wheel alignment settings.

The rig was also run with various tires and various tyre pressures. The second rig served as reference vehicle and was consistently run with optimally aligned wheels and with standard tractor and trailer tires from Michelin.

The trucks were not only equipped with fuel gauges but also with special instruments that monitored exact speed, tyre wear, tyre pressure, rolling resistance and so on. Prior to each test cycle the two rigs were first driven for one hour on the track to warm up the engine, transmission and rear axles in order for the tests to be as reliable as possible. The test engineers made adjustments in the test results for factors such as wind, rain and temperature. The tests took two weeks to complete and the total mileage for the test cycles was just over 1000 kilometers.