Tire rolling resistance

The tread is desigaed and compounded for abrasion resistance, traction, low rolling resistance, and protection of the carcass. It often is divided iato two subcomponents to maximize performance the outer tread for surface contact, and the undertread for tying iato the carcass while reduciag tire rolling resistance through decreased hysteresis. 

Now a closer look at the mapping of vinyl PB can be considered. A further refinement of the total PB citations revealed 926 references for vinyl PB, which are mapped in Fig. 4. Here, the aqueous preparation of syndiotatic 1,2-PB is seen along with the use of both syndiotatic and atactic PB in tire beads, silica containing treads, and even medical applications after cross-linking with peroxide or radiation.Mixtures of catalysts have been used to allow amorphous 1,2-PB to be coproduced with syndiotatic PB in the same reactor.Epoxidized vinyl PB can be used to reduce tire rolling resistance, toughen resin, and stabilize PVC... 

We have shown that the mechanical loss of the cord contributes to the tire rolling resistance and to the acceleration of fatigue process. In order to minimize the effect of this contribution, therefore, one has to minimize the mechanical loss of the cord. This can be achieved in many ways. Of particular Interest are ... 

The reasons for the increase have been attributed to improved green strength, increase in component-to-component adhesion, improved tear strength, lower tire temperatures generated under loaded dynamic service conditions, and lower tire rolling resistance to improve vehicle fuel efficiency. 

When considering only solution polymers, polymer microstructure has a greater effect on tire tread compound performance. Table 9.11 illustrates the impact on tire traction, rolling resistance, and tread wear of a polybutadiene tread on which the vinyl-1,2-butadiene level had been increased from 10% to 50% (Brantley and Day, 1986). The corresponding drop in wear and increase in tire rolling resistance are in agreement with the empirical rules presented by Nordsiek (1985), who attributed such tire property trends to the polymer Tg. 

Reduction of carbon black loading lowers tire rolling resistance. At a constant black loading, an increase in oil level will increase rolling resistance but also improve traction (at low oil levels, an increase in oil level may decrease compound hysteresis by improving carbon black dispersion). 

An increase in the broad aggregate size distribution decreases the tire rolling resistance with constant surface area and DBF. 

To exploit the results of work such as that of Hess and Klamp in improving tire rolling resistance, Swor and coworkers have developed new-technology N 200 series carbon blacks that they claim will give a better balance of tire performance properties, and the general principles will be applicable to a range of tire designs (Hess and Kemp, 1983). 

An example of the impact of product usage and the environmental implications is tire rolling resistance and its effect on vehicle fuel consumption. Reduction in tire rolling resistance results in a drop in vehicle fuel consumption. This has an immediate impact on the generation of exhaust gases such as carbon monoxide, carbon dioxide, and nitrous oxide. 

The crown area of the tire, which includes the tread and belts, accounts for approximately 75% of the radial passenger tire rolling resistance. Improvements in the hysteretic properties of the tread compound will therefore enable a reduction in tire rolling resistance and consequent improvements in vehicle fuel economy. The crown area and particularly the tread compound also affect the life cycle of the tire. Longer-wearing tires (including retreading) delay the point in time when used tires must enter the solid waste disposal system. 

On the other side of the ledger stands an enormous opportunity to prevent emission of 4,750,000 t/a CO2 [67], since the lower tire rolling resistance results in correspondingly lower fuel consumption levels. This balance does not yet include accidents, and later sequelae of accidents, avoided because of enhanced driving safety factors. 

N. Yoshimura, M. Okuyama, and K. Yamagishi, The Present Status of Research on Rolling Resistance in Japan, p. 51, in Symposium Tire Rolling Resistance, D. J. Schuring, ed.. Rubber Division Meeting, Am. Chem. Soc., 1983. 

Some of the critical properties associated with SBRs that can relate to their performance in a rubber compound are the Mooney viscosity (ASTM D1646), which crudely relates to its average molecular weight, and the percent bound styrene contained in the polymer. Higher bound styrene can increase tire traction but decrease tire rolling resistance. The most common percent bound styrene level is 23.5%. 

There is some history of shortages in hydrated precipitated silica because of increasing demand brought on by the need for improvements in tire rolling resistance and the fact that there are relatively few producers of this filler. 

Silanes as a group are essential for precipitated hydrated silica to impart better dynamic properties, such as lower tire rolling resistance, to a rubber compound. 

---