ISO INTERNATIONAL STANDARD 19940 First edition 2017-11 Tyre stiffness index testing procedure for passenger car extended mobility and run flat tyres Procedure d'essai de I'indice de rigidite de pneumatiques a mobilité étendue et pour roulage a plat pour voiture particuliere Reference number ISO 19940:2017(E) so @ IS0 2017 hout license from IHS Not for Resale, 12/01/2017 01:19:09 MST IS0 19940:2017(E) COPYRIGHTPROTECTED DOCUMENT IS02017,PublishedinSwitzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org @ IS0 2017 - All rights reserved Not for Resale, 12/01/2017 01:19:09 MST IS0 19940:2017(E) Contents Page Foreword ..iv 1 Scope .1 2 Normative references ..1 3 Terms and definitions 4 Test method .3 4.1 General .3 4.2 Inflated tyre Vertical stiffness measurement ..4 4.2.1 Tyre inflation pressure 4 4.2.2 Tyre positioning .4 4.2.3 Rims 4 4.2.4 Equipment minimum requirements ..4 4.2.5 Machine set-up 4 4.2.6 Maximum testing load 5 4.2.7 Procedure.. .5 4.3 Zero inflation pressure tyre - Structural stiffness determination .6 4.3.1 General. .. 6 4.3.2 Mathematical model of the vertical forces .7 4.3.3 Quality of the approximation. ..8 4.3.4 Mathematical model of the total stiffness. .8 4.3.5 Deflection calculation .8 4.3.6 Structural stiffness calculation. .9 4.4 Structural part of the TSI. ..9 4.5 Air part of the TSI .10 4.6 Tyre stiffness index (TSI) calculation. .10 Annex A (informative) Test report example ..12 Bibliography .13 iii se with ANSI ed without license from IHS Not for Resale, 12/01/2017 01:19:09 MST