In a modern auto with a downsized engine, a 5% mass reduction leads to 4% lower fuel consumption in city driving, according to calculations made by the U.S. Environmental Protection Agency. And there is a relatively easy way to increase a vehicle’s MPG further. Reducing the unsprung rotating mass has proven to generate a 5 times greater effect on a vehicle, compared to reducing sprung weight. Thus when 1 kg of unsprung rotating mass is removed, it then equals to removing 5 kg of the sprung mass on the chassis. Effectively, that means if you reduce the weight of rims, tires or brakes by only 1% of the total vehicle weight -- it will result in 4% fuel economy.
Kyonggi Bus is the largest bus service (>5000 vehicles) in Korea. The company reported 3% fuel savings after switching to forged aluminum wheels that weigh around 30% less than the steel wheels they had used before. Over time, Kyonggi Bus also confirmed a 10% increase in tire life cycle and a 16% increase for brakes longevity (data provided by Alcoa). Since forged magnesium wheels provide an additional 20% weight reduction compared to forged aluminum, their use leads to higher savings.
Benefits of lightest wheels stretch far beyond reduced fuel consumption:
- Fuel economy and lower air pollution
- Longer life cycle for brakes and tires due to high heat dissipation ability and low weight
- Less pressure on suspension system on uneven roads
- Improved driving experience (easier turning, faster acceleration and deceleration, less vibrations)
- Extended use period (modern magnesium wheels bend rather than crack and withstand bad weather conditions without any signs of corrosion)