Road transport accounts for 18% of all fossil-based CO2 emissions caused by human activity, with tires representing 4% from the fuel used to overcome their rolling resistance. This is roughly the equivalent of one full tank out of every five for a car and one out of three for a truck. To limit the average increase in global temperatures to 2°C in 2100(1), carbon emissions must be halved by 2050(2), even though the number of vehicles on the road and total distances driven are expected to double by that time.