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- Sandberg, Ulf, et al.
(författare)
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Noise emission, friction and rolling resistance of car tires : Summary of an experimental study
- 2000
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Car tires are supposed to be constructed for safe,economical, pleasant and environmentally friendlydriving. Three performance measures that would quitewell represent the major operational characteristics oftires within the mentioned topics would benoise emission, wet friction and rolling resitance.Since the latter affects fuel consumption it alsoaffects economy and exhaust emissions.It is sometimes claimed that when trying to reduceexterior noise emission, there is a conflict withfriction and perhaps also with rolling resistance. Theimplication would be that one could not reducetire/road noise any further without sacrificingsafety or economy. A European Union directive withnoise emission limits for tires is underway. It hasbeen suggested that tires should meet certain limitsalsowith regard to friction; assuming a conflict betweenrequirements for low noise and high friction.Consequently, it is important to study this matterfurther.Earlier studies have indicated that there is noconsistent conflict between friction and noisecharacteristics with respect to road surfaces. For12 tires tested on 5 surfaces Denker found nosignificant noise-friction correlation, until henormalized friction values in an unusual way, in whichcasehe found weak conflicts between noise and friction.Tests in 1992 by Nelson for 16 car and 9 trucktires indicated weak noise-safety correlations,suggesting a conflict between the parameters, but thiscould well have been biased by the inclusion of a widerange of tire widths. According to Ejsmont, ageneral conflict between noise and rolling resistanceproperties could not be found. A recent andquite comprehensive study in Germany, made on 48car tires, concluded that neither was there anycorrelation between noise and rolling resistance, norbetween noise and "wet braking". The same wasfound between noise and aquaplaning speed.These authors conducted a pilot study in 1997 with thepurpose to establish relations betweenexterior tire/road noise, wet friction and rollingresistance of current car tires. The firstconclusionssuggested that there is no significant conflictbetween friction and noise or between rollingresistance andnoise. This study was limited to 28 tires so it wasdecided to continue with testing in order to gethigherconfidence of the results and to examine altogetherabout 100 modern car tires of similar size. Theresultsof this study, which is believed to be the mostcomprehensive study of these relations so far, arepresented here.
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