5.3.1.3 Tyre pressure effect As mentioned in the previous paragraph tyre pressure is maybe the most important factor affecting rolling resistance of a tyre in use. Maintaining proper tyre inflation is essential for both fuel efficiency and better tyre performance. Bandenspanning is wellicht de belangrijkste factor voor de rolweerstand. Het handhaven van een correcte bandenspanning is essentieel voor zowel het brandstofverbruik als het functioneren van de band(grip). Deflated tyres can cause up to 8% increase in fuel consumption while reducing tyre lifespan by 45% [Hakanen and Jukka]. Slappe banden kunnen tot 8% meer brandstofverbruik en een vermindering van de levensduur van de banden met 45% veroorzaken. According to Pirelli (www.pirelli.com) under normal driving conditions the tyres lose 1-2 psi of pressure per month while the tyre pressure should - in some cases- be higher than the standard values, in order to compensate for heavier vehicle conditions. Additionally a tyre may lose up to half its air and not seem to be under-inflated. Een band kan half leeg zijn zonder dat men dat ziet. It should be reminded that insufficient pressure is the main cause of tyre damage and the air-tightness of a tubeless tyre or of the inner tube is not completely guaranteed if a valve cap with seal is not used. Finally deflated tyres are an important factor causing road accidents resulting in numerous fatalities and injuries throughout Europe. Despite the fact that tyre pressure is important for the operation of the vehicle car owners are not careful with the condition of their tyres. A research conducted by TNO for the Dutch Ministry of Environment showed that 50% of all cars are driven on under-inflated tyres [IEA 2005]. Uit onderzoek van TNO voor het Ministerie van Milieu blijkt dat 50% van alle auto's met te slappe banden rond rijdt. In the US it is estimated that under-inflation causes an increase in the average rolling resistance of about 8% [NRDC 2004]. According to data provided by Michelin the tyres in service are on average 0.2 to 0.4 bar deflated, a fact that corresponds to an increase in fuel consumption of 1 to 2.5% [Penant 2005]. Another important characteristic of additional rolling resistance caused by tyre deflation is that it is a totally 'real-world phenomenon that does not affect at all type approval tests. Therefore it must be accounted amongst the factors that differentiate real world energy performance of a vehicle from type approval and thus it is difficult to control through legislative measures. Bron: CO2-emissions from passenger cars Contract nr. SI2.408212, onderzoeksrapport voor de Europese Commissie   Het volledige rapport, van ruim driehonderd pagina's, vindt u op: http://ec.europa.eu/enterprise/automotive/projects/report_co2_reduction.pdf