A tyre is the most critical point of contact a vehicle has with the road. If one tends to manage them well, it not only handpicks the bumps out of a journey, but also contributes towards increasing vehicle fuel efficiency, the biggest cost factor for fleet operators
Irrespective of your vehicle type, an optimal tyre choice directly impacts of a truck's fuel consumption. Especially for a long haul truck that demands low rolling resistance grade tyre as well as low friction rubber compound, using a non-optimal tyre can cut down fuel efficiency by up to three percent as well as reduces tyre life. Rolling resistance can amount to up to nine percent of a truck's fuel consumption and every minuscule increase in fuel consumption counts for a fleet operator. A new tyre can have up to three percent of fuel consumption against the run-in tyre thus need optimised maintenance.
The Sweet Spot
Most of the countries across the world (including European Union) have well defined the regulations wherein tyre labeling needs to clearly define tyre performance, external rolling noise, wet grip as well as cover fuel efficiency. Labelled grade A to G, with A being the most fuel efficient and G being the least one, there is an increase of 2.5 percent in fuel consumption for every increase in rolling resistance grade.
A fleet operator will try and maximise fuel efficiency for a long haul trip, thereby opting for tyres with low rolling resistance. This is largely opposite of urban transport applications where the operator will opt for more durable tyres. Thus, it is crucial to find the sweet spot among service life and fuel efficiency. However, what still remains out of EU's purview in labelling is the durability, cornering, stability, braking efficiency on dry roads, retreading, ability to compensate for road irregularities as well as the total performance.
A tyre's air pressure is among the most important factors to maximise tyre performance. Various tests conducted show tyre air pressure, as little as one bar too low will raise fuel consumption by up to 2 % and will reduce the tyre’s service life by around 20 %. Under-inflated tyres also increases braking distance as well as reduces control over the vehicle and its manouverability. In case a truck is on full load, inflation pressure should generally be around 8–9 bars. However, air pressure must be related to the actual axle load. On the drive axle, as low pressure as the load allows in order to get a long and wide foot print (braking and traction forces). High pressure is recommended for all free rolling wheels, since this strengthens the shoulder area on the front bogie and trailer axles.
A normal tractor also demands aligned axles as it reduces air resistance as well as tyre rolling resistance. This is because misalignment can increase fuel consumption by upto three percent and raise to 15% in case the trailer wheels are also not aligned. Such misaligned trailers also lead to reduced vehicle stability & control, as well as additional tyre wear and tear. According to industry experts, around 80% of wear on a truck’s front tyres is actually caused by misaligned rear axles.
To ensure you that you get the most out of the investment you make into tyres it’s important to check vehicle's operating conditions. Various factors such as season, wheel alignment, load conditions, highway or off highway conditions dominate the overall tyre performance. How you use the tyre and maintain them for maximised total cost of ownership is still a million dollar question.