Abstract

This article attempts to write a mechanical justification of the ISO 18164 norm from a mathematical point of view. There are only minor differences between the final equations and the ones used in the norm. Indeed, this work is a formal derivation of what is already known.

The main point of this article is a proper writing of the first law of thermodynamics.

The main difference between physical equations and the ones used in the ISO 18164 standard is that the norm neglects the variations of the bearing friction of the tire and of the drum between the skim test and the loaded one. The order of magnitude of the bearing friction term is approximately 0.1 kg∕t at 80 km∕h.