Tire Size Research Articles

Effect of rear tyre dimensions of tractors and tractor traffic in potato cultivation

In experiments with different rear wheel tyre sizes of tractors for cultivation work in potato fields, two passes of tractor wheels for each cultivation brought about a decrease in yield as compared with a single pass. Different sizes of rear tyres did not appear to have a marked effect on potato yields. Tractor traffic when spraying against the potato blight in the later part of summer decreased the yield of tubers. In three experiments cultivation by hand resulted in higher yields than tractor cultivation. Soil physical investigations showed the total porosity of the soil to be lower after two passes of tractor wheels than after a single pass. There were no pronounced differences between tyre size treatments, however. The air porosity at a depth of 10–15 cm under the wheel tracks was lower for a tractor with a disc implement than with a tined one, and lower in the furrows than in the ridges. There was an almost linear increase in slip with increasing gradient, and a higher slip for the 11 × 28 in than for the 9 × 36 in tyre. At steeper gradients, it was not possible to measure the slip of the 6 × 36 in tyre on account of digging into the ground. A pronounced sideways sliding of the tractor with 6 × 36 in tyres was observed where the row direction was at an angle to the fall of the land.

A study of the effects of wet surface soil conditions on the performance of single wheel

This paper presents of a test programme conducted to determine the effects of wet surface soil conditions on the performance of pneumatic tyres. Two fine-grained soils were used, one that was highly plastic (heavy clay) and one that was only slightly plastic (silt). The surface soil conditions were of three types: “as compacted”, flooded and drained, flooded and undrained. Most of the tests were conducted with the heavy clay using a tyre size of 6.00–16 and a deflection of 35 per cent. The four tread conditions tested were a smooth tyre, a directional tread, a non-directional tread and a smooth tyre with traction aid. Test results showed that in soils exhibiting non-uniform strength profile of the type and extent of the non-uniformity largely controlled the performance. As a result, the value used to describe the soil characteristics in relation to performance should be varied accordingly. For a given wheel load, the loss of pull due to flooding, expressed as a percentage of the pull in the flooded condition, is a constant for each tread pattern. The tread pattern does not materially affect the performance in the slippery condition so long as the tyre is not smooth. However, in the unflooded condition the tread pattern can make a considerable difference in performance. It was found that a peak performance was attained at a specific load, regardless of tread pattern or soil condition. It was also found that repetitive traffic had no effect on pull through five passes in the “as compacted” condition. However, for the flooded soil the pull increased with traffic in the drained condition and decreased with traffic in the undrained condition. The level of performance depends to some extent on the duration of flooding. The lowest pulls were attained when the flooding period was very brief and the soil strength was high. Although the sheargraph tended to reflect the influence of surface conditions on performance for all soil conditions, the relations developed were very broad.

Relevance of Elastic and Loss Moduli of Tire Components to Tire Energy Losses

Abstract This study of energy losses in tires was undertaken to obtain a better understanding of the contributions of tire components, and to relate them more precisely to laboratory measured dynamic properties. Details are given of a general method of analysing total tire energy losses into components due to the tread, sidewall, textile and carcass rubber. The method entails measuring the losses, as determined by rolling resistance experiments, of tires in which the composition of the components has been varied systematically. The results have been correlated to the dynamic properties of the tire components, and the tire parameters, deflection and inflation pressure. The method has been applied to two extreme sizes of tires, 9.00–20 and 2.25–8. The work described in this paper will enable the tire designer and rubber and textile technologist, to predict with greater certainty the effects on tire energy losses of any changes in tire materials and will also give them more guidance in formulating these changes.

Tyre sizes: 68. J. Maring.Landbouwmechanisatie, 1964, 15 (8) 817–820; 820; illus. (Du.e.).

Tyre sizes: 68. J. Maring.Landbouwmechanisatie, 1964, 15 (8) 817–820; 820; illus. (Du.e.).

Applications

For modern automobiles the tire sizes range from 5.50-15 to 8.20-15. What do these numbers mean? If they are true sizes, there should be units of measurement included or implied. What are the units? Does a person have to measure his old tires, or have them measured, when they need to be replaced? Perhaps these numbers are only for classification or cataloging and are not true sizes or measurements. Is that true? What about the point in the number before the dash? Is it a decimal point?

Ultrasonic Method of Tire Inspection

The principles of a method are discussed for detecting internal defects in pneumatic tires, such as ply separations, by the attenuation of transmitted ultrasonic waves. Equipment for carrying out tire inspections by this method is described. It includes provisions for inspecting a large range of tire sizes, scanning the tread region from shoulder to shoulder and is suitable for operation by inspection personnel. A useful form for recording the results of a tire inspection is described. One of the principal applications for this method of inspection is the examination of tires to determine their suitability for recapping.

An Investigation of Stresses in Public Service Vehicle Type Wheels

The causes of failure in wheel rims has been only recently investigated and this paper is a contribution dealing with public service vehicle type wheels. Various types and sizes of wheel are considered, statically and dynamically, with differing tyre sizes. The results obtained with wire resistance strain gauges are claimed to be more reliable than those achieved by the deflexion method. Stresses in the critical parts of a wheel are produced by assimilating the forces which would be experienced in service, including bumps, corners, and braking. The influence on wheels of acceleration on corners and deceleration due to braking is examined and results shown. Stress analysis of a wheel is only part of the design problem, since residual stresses induced during manufacture, the properties of the material and the order of severity of service conditions have also to be taken into account. The investigation concludes with a comparison of a welded wheel and a riveted wheel, but the latter has received wider consideration. It is not claimed to be a complete investigation suitable for establishing a design procedure, but results obtained provide much useful information.

Airplane Tires and Wheels

Abstract This paper tells of some of the mounting conditions of airplane tires on wheels, and of the relation between static load, ultimate cushioned load, and energy capacity. Static and dynamic loading curves and corresponding hysteresis loops are also presented, and the forces and power losses are resolved horizontally and vertically. Results of extensive wind-tunnel tests show the effects of tire size, wheel size, safety-tread design, streamlining, and tire misalignment.