HVIA in PBS tyre analysis clarity call

Concern that some currently approved PBS designs may fail standards

HVIA in PBS tyre analysis clarity call
Greg Forbes


With tyre choices under Performance Based Standards (PBS) the subject of continuing industry and regulatory focus, Heavy Vehicle Industry Australia (HVIA) is emphasising its importance.

A review of tyre management practice in the Australian PBS system recommends a system based around the use of standard tyre characteristics for all PBS assessments.

The National Heavy Vehicle Regulator (NHVR) had commissioned independent road safety expert Dr John de Pont from Ternz Transport Research to look at simplifying the treatment of tyres under the PBS scheme.

HVIA policy and government relations manager Greg Forbes says that selecting the correct tyres for PBS vehicles has been a significant source of confusion for many in the industry.  

"Dr de Pont suggests that all PBS assessments should use the data for Michelin XZA tyres which were used to establish the initial performance standards for the PBS scheme," Forbes says.

"Dr de Pont acknowledges that an operator’s choice of tyres will impact on the performance of the PBS vehicles against the relevant PBS standards.

"He essentially argues however, that that if PBS vehicles are analysed using the same tyre characteristics that were used for the initial analysis on which the PBS system is based, the variation of performance of the PBS vehicles based on choice of tyres is likely to be similar to the variation in performance of prescriptive vehicles using the same tyres."

Similarly, the variation of tyre performance can be compared to today’s PBS fleet and will have minimal impact on the original standards.

The report proposes a method for interpolating the initial tyre data set to allow it to be used by the various simulation packages currently in use by PBS assessors.

"He also proposes that the NHVR should provide a methodology for specifying the nominal rated load for each tyre size which would apply to all brands," Forbes adds.

Read about the options for tackling tyre data, here

Dr de Pont also suggests that the impact of relaxation length, and the reduction in cornering force due to longitudinal slip are not significant and do not need to be modelled.

"The report acknowledges that the proposed approach means that some currently approved PBS designs – particularly truck and dog and A-double combinations – which rely on high performance tyres to meet the standards may no longer meet the standards under the proposed approach and may need to be modified," Forbes says.

"This will need to be investigated further to see if any transitional arrangements will be required."

The NHVR is holding a workshop in Sydney today to discuss the results of the report and HVIA is to comment on the outcome in due course.


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