ISO 11795:2018

Name: ISO 11795:2018 — Agricultural tractor drive wheel tyres — Explanation of rolling circumference index (RCI) and speed radius index (SRI) and method of measuring tyre rolling circumference
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Agricultural tractor drive wheel tyres — Explanation of rolling circumference index (RCI) and speed radius index (SRI) and method of measuring tyre rolling circumference

Название (английский):

ISO 11795:2018

Agricultural tractor drive wheel tyres — Explanation of rolling circumference index (RCI) and speed radius index (SRI) and method of measuring tyre rolling circumference

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 5
Дата публикации:: 28 июня 2018 г.
Издание:: ISO IS 11795 edition 2 version 1
ICS:: 83.160.30

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Описание (английский):

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).

Abstract

Похожие стандарты

Стандарты, упомянутые в описании

Overview

ISO 11795:2018 - "Agricultural tractor drive wheel tyres - Explanation of rolling circumference index (RCI) and speed radius index (SRI) and method of measuring tyre rolling circumference" - specifies a repeatable method for measuring tyre rolling circumference for new agricultural tractor drive‑wheel tyres (diagonal and radial). The standard also explains the Rolling Circumference Index (RCI) and the Speed Radius Index (SRI) used for tyre selection, coupling and theoretical speed calculations.

Key topics and technical requirements

Test scope: Measurement of rolling circumference for new tyres mounted on representative drive axles under loaded conditions.

Mounting and pairing: Tyres must be mounted singly on approved rims and paired (same size, type, brand) with exterior diameter matching within 0.5% when unladen and inflated.

Load and inflation: Each tyre is loaded to the maximum load printed on the sidewall; inflation pressure is the reference pressure corresponding to the 30 km/h load (inflation with air only).

Preconditioning: Tyres are run 30 minutes at 25 km/h ±5 km/h (or until pressure stabilizes) before measurement.

Measurement procedure:

Test speed: 10 km/h ±2 km/h.
Track: straight, level, smooth and dry (asphalt or concrete).
Distance: minimum 100 m; at least 1 000 impulses recorded per test.
Instrumentation: each test tyre must provide at least eight pulses per wheel revolution; distance may be measured directly or with a calibrated fifth wheel.
Two runs in each direction; average of eight observations (4 runs × 2 tyres) used to compute rolling circumference.

Calculation: Rolling circumference RC (mm) = 1000 × S (m) × ipr / n, where S = track length, ipr = pulses per revolution, n = mean impulses recorded.

Environmental limits: Ambient temperature 5 °C to 30 °C; wind ≤ 15 km/h.

RCI and SRI:

RCI provides a logical progression of rolling circumferences (each step ≈ 5.4% larger). RCI values have tolerances (±0.2). R‑1 and R‑1W tyres are recommended to use integer RCI values; R‑2 RCI values are typically +0.5.
SRI is a convention for calculating theoretical tractor speed during homologation/interchangeability and is not a directly measurable circumference.

Practical applications and users

Useful for tyre manufacturers, tractor OEMs, test laboratories and regulatory bodies to:

Ensure correct tyre coupling for 4WD tractors (minimise driveline penalties from mismatched rolling circumferences).
Define tyre designations and RCI/SRI markings for interchangeability and homologation.
Produce authoritative test reports supporting tyre selection and vehicle calibration (speedometers, transmission matching).

Related standards

ISO 4251‑1, ISO 4251‑2 (tyre & rim designations, load capacities)

ISO 7867‑1, ISO 7867‑2 (metric series tyres for agricultural machines)

ISO 8664 (radial drive‑wheel tyres designation and use)

Keywords: ISO 11795:2018, rolling circumference index (RCI), speed radius index (SRI), tyre rolling circumference, agricultural tractor drive wheel tyres, method of measuring tyre rolling circumference.

ISO 11795:2018

Abstract

Похожие стандарты

Overview

Key topics and technical requirements

Practical applications and users

Related standards

Технические детали

BS ISO 4251-1:2019

Code designated diagonal tyres (ply rating marked series) for agricultural tractors, trailers and machines. T…

ISO 4251-2:2017

Tyres (ply rating marked series) and rims for agricultural tractors and machines — Part 2: Tyre load ratings

ISO 7867-1:2018

Metric series for agricultural, forestry machines and construction tyres — Part 1: Tyre designation, dimensio…

ISO 7867-2:2018

Metric series for agricultural, forestry machines and construction tyres — Part 2: Load ratings for agricultu…

ISO 8664:2018

Tyres for agricultural tractors and machines — Code-designated and service-description marked radial drive-wh…