Abstract

A tire was measured to determine its average groove depth by each of several operators in each of seven laboratories in the morning and afternoon for two consecutive days. The results show that the operators repeat their measurements within acceptable variation. On averages of six measurements by a single operator, a difference of 0.002 in. (0.05 mm) was significant. The variability of operators' averages around their laboratory average was the same for all laboratories except one. However, averages among laboratories were different, which is attributed to small differences in the measuring practice. The precision of wear rate estimates based on the difference of average groove depths before and after a period of wear is estimated and ways in which the precision of estimates of wear rates can be optimized are suggested.

Abstract

Laboratory tire tests for dynamic spring rate and damping, steady state forces and moments, rolling radius, and cornering force transient measurements are described. Data are shown for bias, belted bias, and radial constructions in a range of automobile tire sizes. The significant differences in the results are noted on all tests for the three tire constructions.

Abstract

The lowest natural frequencies of a bias tire under inflation pressure are deduced by assuming the bias tire as a composite structure of a bias‐laminated, toroidal membrane shell and rigorously taking three displacement components into consideration. The point collocation method is used to solve a derived system of differential equations with variable coefficients. It is found that the lowest natural frequencies calculated for two kinds of bias tire agree well with the corresponding experimental results in a wide range of inflation pressure.

Abstract

Tire tests were performed under time‐varying inputs on the Calspan Tire Research Facility with a G78‐14 belted tire at low speeds and path frequencies up to 6 rad/ft (20 rad/m). Both slip angle and vertical load were varied, either separately and periodically or in combination. The combination simulated actual time histories of slip angle and load measured in road accident avoidance tests.

For path frequencies up to 0.2 rad/ft (0.7 rad/m), attenuation of lateral force and aligning torque amplitudes was negligibly small. However, both lagged static values substantially, leading to dynamic offsets in these quantities. The offsets appeared to be the most significant factors for tires. Their effect on the dynamic response of a vehicle remains to be investigated.