ISO 11795:2018 農業用トラクターの駆動輪タイヤ—転がり円周指数（RCI）と速度半径指数（SRI）の説明、およびタイヤの転がり円周の測定方法 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 31, Tyres, rims and valves, Subcommittee SC 5, Agricultural tyres and rims.

This second edition cancels and replaces the first edition (ISO 11795:1997), which has been technically revised. It also incorporates the Amendment ISO 11795:1997/Amd.1:2010.

Introduction

Matching front and rear wheels with different tyre sizes on four-wheel drive agricultural tractors requires accurate rolling circumference values. The test method to determine rolling circumference outlined in this document was developed to follow this requirement. The values thus obtained are not intended for use as levels of performance or quality.

The test speed has been set at typical working speed when the four-wheel drive will likely be engaged and the most critical match is required. Generally, the four-wheel drive is disengaged at road speeds. Therefore, the determination of rolling circumference is not related to the tyre's maximum speed, e.g. 30 km/h or 40 km/h. Nevertheless, other speeds or conditions may be run provided it is clearly documented in the results.

1 Scope

This document specifies the method for measuring rolling circumference for new tyres, under loaded conditions, made for use on agricultural tractors and machines, and applies to agricultural tractor drive wheel tyres in diagonal and radial construction. It also includes an explanation of the rolling circumference index (RCI) and speed radius index (SRI).

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

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