Low-friction tires
Low-friction tires are tires that have reduced rolling resistance.
This is achieved through the following measures:
- Use of special rubber compounds
- lower carcass height
- radial reinforcement ( radial hoop )
- Use of special profiles or smooth running surfaces
- lower tire mass
- no or special hose
- Height of the rim flange (on the bike)
Depending on the application, other measures are most effective for achieving smooth running. The application limits for tires are determined by:
- Axle load
- speed
- Road surface condition
Potential savings
The differences for the same tire dimensions are up to 30 percent with the same profiles. Off-road tires have much higher rolling resistance due to their coarser treads. As a result, the following reductions in consumption can be achieved in passenger cars powered by Otto engines:
- City traffic 4–6%
- Extra urban 3–5%
- Motorway 2-3%
For electric vehicles or low-energy vehicles , there are significantly higher consumption reductions between 15% and 50%.
In the bicycle sector, the rolling resistance can fluctuate even more, as there are greater differences in design and pressure (e.g. three times).
Rubber compound
A lower rolling resistance is achieved by using special silica or silica-silane compounds instead of carbon black tire compounds based on carbon black. As a result, the adhesion properties on wet roads can be improved or, with the same adhesion properties, the rolling resistance can be reduced.
belt
The belt is the supporting structure. The carcass fabric can be characterized by the threads per inch.
Dimensions
In bicycle tires in particular , carbon fibers are used instead of wire inserts in order to save mass. In heavier vehicles, however, the reduction in rolling friction due to this measure is relatively small.
Cross-section (tire height + rim diameter) times tire width
With lower tires, the flexing work in the tire sidewalls is less. In the case of scooter and scooter tires, elliptical cross-sections have become established which provide good damping despite the low tire height.
Treads
Tires with no profile have poorer coefficients of friction, but lower rolling resistance. Profileless treads are used for wider bicycle tires.
tube
In the case of bicycle tires , the tube is rubbed with talcum powder or coated with it at the factory to reduce friction. Hoses made of latex rubber have less rolling friction than those made of butyl rubber under otherwise identical conditions (internal pressure, hose thickness).
Political measures
In 2003 California passed a law to promote low-friction tires. Until 2007, standards were drawn up by the California Energy Commission (CEC), which will come into force in July 2008 (instead of 2006 as planned). In it, the CEC has laid down recording methods for the manufacturers of tires for light commercial vehicles for their rolling resistance and developed evaluation criteria for the fuel consumption by the tires. The classification of the tires in terms of rolling resistance will then be noted on the tire itself. Studies by the German Federal Environment Agency have shown a positive correlation between rolling resistance and braking distance or risk of aquaplaning .
Others
The tire width and diameter contribute to the running and rolling resistance due to the increased contact area on the road, and also to the air resistance of the vehicle. Wide tires or increased ground clearance due to larger wheels increase the cross-sectional area in both cases.
Individual evidence
- ↑ Car tire list as PDF (PDF) Archived from the original on November 13, 2013. Retrieved on January 9, 2011.
- ↑ Optimization of tires (ProVelo 42 9/95 p. 16 ff.) . rollende-seiten.de. Retrieved July 15, 2019.
- ↑ Fuel savings potential from low rolling resistance tires (Microsoft PPT) Federal Environment Agency. Archived from the original on February 4, 2017. Retrieved July 15, 2019.