Smithers recently announced the addition of three specialized rolling-resistance testing capabilities at its tire and wheel test center in Suzhou, China. These new capabilities enable more comprehensive insight into vehicle operating scenarios by recreating a wider range of real-world conditions in a controlled laboratory environment. ATTI speaks with Henry He, Smithers’ general manager of the materials science and engineering division for Asia-Pacific, about the expanded testing capabilities, the importance of rolling-resistance testing and what these advancements mean for future tire development
How do slip and camber angle variations in rolling resistance testing affect the evaluation of passenger car and light truck tires?
In actual driving conditions, tire performance is significantly influenced by non-linear operating parameters that are not captured during standard straight-line, steady-state testing. Tires on both passenger cars (PC) and light trucks (LT) routinely operate under dynamic slip and camber angles. These angles arise from routine factors such as wheel alignment settings, cornering maneuvers, lane changes, changes in vehicle attitude (e.g., pitch and roll) and external forces (e.g., crosswinds and sloped roads).
The incremental resistance under these non-linear conditions is greater than the resistance observed under laboratory-based, straight-line conditions. This fundamental difference means that more can be learned about actual RR performance when these new laboratory tests are applied.
Why is high- and low-temperature rolling resistance testing important for truck and bus radial (TBR) tires, and how does it relate to vehicle range in winter conditions?
Theoretically, temperature exerts a notable influence on the rolling resistance (RR) of all tires. This concept has been empirically supported by our prior work on high- and low-temperature RR testing for passenger car radial tires (PCR) and LT tires (testing began in 2022; see the ‘Effect of Temperature on Tire Rolling Resistance‘ white paper for detailed data). Further evidence has been provided by some original equipment manufacturers (OEMs) who have conducted vehicle testing confirming this effect on TBR tires. With fuel being the largest variable cost for trucking fleets, successfully achieving improvements in low-temperature RR could provide a positive impact on fuel efficiency and operational cost savings.
How does including chassis components in rolling resistance testing help tire manufacturers understand the tire’s contribution to overall vehicle resistance and optimize tire performance?
Current laboratory testing to internationally recognized standards only yields the tire’s rolling resistance coefficient (RRC). This singular value fails to represent real-world vehicle operation where tire resistance exists as part of a complex, coupled system that includes frictional, deformation and aerodynamic resistance from the entire tire-chassis assembly (including shock absorbers, hubs, bearings, brake calipers and driveshafts).
To address this, the proposed testing methodology involves measuring the comprehensive resistance of the integrated tire-chassis system. By comparing this full-system test with the baseline tire-only test, we can more accurately separate the tire’s contribution from the additional resistance due to the chassis components.
This inclusive testing of chassis components provides OEMs and chassis component suppliers with a better understanding of resistance from a complete system perspective, moving beyond the isolated tire perspective, to drive true energy efficiency gains.
How does Smithers’ approach to replicating real-world driving conditions in a laboratory setting improve the accuracy and relevance of rolling resistance data for tire and vehicle performance?
OEMs have identified notable gaps between actual real-world energy consumption figures and simulation results based on conventional RR testing, driving the need for a new approach. The primary value of simulating or replicating real-world vehicle conditions (including diverse operating temperatures and driving scenarios) in a laboratory setting is to reduce this deviation by ensuring that the resulting RR data not only reflects the tire’s inherent characteristics but also quantifies its true performance within the entire vehicle system.
Leveraging this more accurate data for component selection, optimization and energy consumption prediction allows both OEMs and tire manufacturers to effectively reduce the risk of inconsistencies between pre-production laboratory data and the actual vehicle performance. This can simultaneously mitigate the high costs and uncertainties inherent in traditional on-vehicle tests, thereby shortening the test cycle and providing more reliable technical support for crucial product development and market validation decisions.
How are advanced rolling resistance testing methods, such as angle, temperature and chassis-inclusive tests, shaping tire design and performance standards across the automotive industry?
As noted, these advanced testing methods can more accurately simulate and replicate real-world vehicle operation, offering higher practical value than conventional testing. By utilizing more realistic data, OEMs and suppliers can better pinpoint product development improvement areas, shorten development cycles and reduce unnecessary waste. These methods establish a new set of tools for energy consumption modeling and performance optimization.
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