The acclaimed Continental HSR1 tyre has added to its already impressive package of benefits by being confirmed as the lowest-noise steer-axle tyre available in the market. In coast-by tests, the HSR1 (Heavy truck, Steer-axle tyre, for Regional applications) generated a sound pressure level of just 69 dB(A) at a reference speed of 70 km/h. As each 3 dB(A) increase is equivalent to doubling the sound pressure level, this result means that the HSR1 is seven times quieter than the legal limit.

Traffic noise is the most common form of acoustic pollution in the developed world. Taking a truck running on a dry road as an example, above 40 mph the sound generated by the tyres on the road is the dominant noise source. Although this is primarily caused by the texture of the road surface, tyre pattern can play a significant part in its reduction. The development of quieter-running products has therefore become a priority to meet the requirements of recent EU legislation: since September 2003 in Europe, newly-released tyres should be certified and given a check number according to e4-s. From February 2004 all homologated vehicles, and from February 2005 all other vehicles, must be equipped with noise-certified tyres.

For certification purposes, truck tyres are divided into Class C2 (light truck) and Class C3 (heavy truck). For C2, the noise limit range is from 75 to 78 dB(A), and for C3, from 76 to 79 dB(A). Apart from the tyre pattern, other factors affecting the noise made by a tyre are its size and construction. The level of noise generated is only determined for the 'loudest' size, therefore Continental puts its largest tyre in each category forward for testing. With few exceptions, all heavy truck tyres from Continental have received e4-s certification.

"HSR1 achieves its low noise properties through Continental's specially-designed straight-groove geometry," explained Jill Rodgers, Brand Manager of Continental Truck Tyres. "Apart from the obvious benefits of reduced noise to residents living alongside or near busy roads, bus and coach operators in particular appreciate the reduced interior noise for passengers." Optimised noise characteristics have not detracted from the tyre's other properties; it offers the same high mileage and has outstanding wet grip. HSR1 has received technical approvals from truck OEMs DAF, Iveco, MAN, Mercedes, Renault, Scania and Volvo.