BS ISO 4251-2:2019

What is ISO 4251-2 - Code designated diagonal tyres about ? 

ISO 4251-2 establishes the load ratings of the diagonal code designated (ply rating marked series) tyres for agricultural tractors, trailers and machines. 

Note: Code designated diagonal tyres (ply rating marked series) for construction applications (industrial tractors), identified by the classification code R-4, as specified in ISO 18805, or by suffix "IND" are part of ISO 13442. 

Who is ISO 4251-2 - Code designated diagonal tyres for ? 

ISO 4251-2 on code designates diagonal tyres is relevant to: 

• Manufacturers of Tyres 
• Automobiles engineers 
• Mechanical engineers 
• Any entity responsible for testing and quality assurance of tyres and rims 

Why should you use ISO 4251-2 - Code designated diagonal tyres for? 

In diagonal tyres, layers of nylon cord are positioned diagonally across each other in the tread and the sidewalls at an angle of 55 degrees. 

ISO 4251-2 specifies methods and guidelines for the manufacture of tyres with standardized dimensions and quality standards and defines standard ratings for the tyre size designation for agricultural machines capable of carrying heavy loads. 

Overall, ISO 4251-2 is a comprehensive guide for the manufacture of diagonal tyres that lays out the requirements, dimensions and load rating so that users can improve the quality of tyres and make them according to standardized markings so that they can carry heavy loads and be used on any terrain. 

What’s changed since the last update ? 

BS ISO 4251-2:2019 supersedes BS ISO 4251-2:2017, which is withdrawn and includes: 

• Information already contained in other International Standards was removed and replaced with normative references to those standards 
• Radial tyres marked with ply rating and with reference speed of 10 km/h were deleted since obsolete and this document was restricted to code designated diagonal tyres (marked with PR) for agricultural tractors trailers and machines 
• The title of this document was revised accordingly 
• The document was aligned with other International Standards developed by SC 5 and with existing regulations 
• Equivalence of tyre load carrying capacities in case of tyre marked with speed symbol A6 (corresponding to previous load-carrying capacities of tyres marked with PR only) and that of tyres marked with speed symbol A8 was introduced, together with the possibility of a double marking (supplementary service description) 
• Load variations with speed and for specific applications were added 
• Some additional PR versions were added with the corresponding markings of the service description