Grzegorz Ronowski

Road texture influence on tyre rolling resistance

Tyre performance, one of the critical factors for vehicle users, is strongly related to the road surface characteristics, most notably to the pavement texture. Phenomena that occur at the tyre/road interface affect tyre friction (skid resistance), rolling resistance, tyre wear and tyre/road noise. This article deals with relationship between surface texture and rolling resistance of light and heavy vehicle tyres. Mean profile depth (MPD) is one of the most common descriptors of road surfaces and in many studies it is correlated with rolling resistance of tyres. Results of measurements performed by the Technical University of Gdańsk show that although the correlation exists, it is not very strong and regression between MPD and rolling resistance is not linear. The key reason for this is partial enveloping of the tyre tread interacting with pavement texture. The article presents results of laboratory and road measurements of rolling resistance performed on road surfaces characterised by MPD from 0.20 up to 4.75u2005mm and the correlation of the rolling resistance coefficient with MPD. Certain aspects of texture enveloping and influence of this phenomenon on rolling resistance are discussed.

Tyre rolling resistance and its influence on fuel consumption

Rolling resistance of tyres is one of the major resistive forces acting on any wheeled vehicle. Unfortunately, it is also one of thenforces very difficult to measure. It is estimated that in certain traffic conditions (like for example constant speed driving with slow ornmoderate speed) so called Rolling Resistance Impact Factor may be as high as 0.3. This means that reduction of rolling resistance by 50% would lead to 15% of energy savings. The paper presents road measuring method of tyre rolling resistance and unique equipment used by the Technical University of Gdansk designed to perform measurements of passenger car tyres. It also discusses road pavement, tyre and environmental conditions influence on rolling resistance. Also selected data describing current situation related to rollingnresistance on different road pavements and rolling resistance of modern passenger car tyres including tyres specially designed fornelectric and hybrid vehicles are presented.

Design and Calibration of Rolling Resistance Test Trailer R2Mk.2

The paper describes construction and calibration procedures of the rolling resistance test trailer R2 Mk.2. The trailer is design to measure rolling resistance of passenger car tyres in various road conditions on trafficked roads. The trailer utilizes so called angle method also known as vertical arm method. The paper presents also calibration procedures that are necessary to ascertain good precision of the measurements.

RESEARCH ON OPERATIONAL CHARACTERISTICS OF TYRES WITH RUN FLAT INSERT

The paper describes results of research on heavy vehicle tyre with Run Flat VFI insert. The experiment has included the determination of heat generation, rolling resistanceand radial stifnessof two different tyre designes (textile and steel carcass). The results have been used for the purpose of ewalution of tyre operating characteristics. The study included research on non-inflated tyre properties. The purpose of the paper is nto determine chracteristics of the tyres equipped with inserts, which are essenical for driving wheeled APCs. The inserts are composed of polymer rings mounted on rims inside the tyres. If the inflation pressure of the tyres is very low or of there is no inflation pressure at all, the rings transfers the loads imposed on the tyre to the run. Usually in such a case, there is coctact of the ring and inn er surdace of the tyre tread area. Laboratory facility for surveys of heavy vehicles tyres summary characteristicsof radial stiffness and histeresis of the tyres, temperature destribution on the external surface of the test tyre, comparison of radial characteristics of the tyres tested, example of stiffness characteristics, destribution of the temperature on the side of tyre during the road test and carcass damages on the flat tyre are presented in the paper.