Proposal to modify performance calculations and limits under UN R55. Currently UN R55 prohibits a vehicle combination with required performance values Dreq, Dc-req, Vreq and Sreq where Dc-cert ≤ Dc-req ≤ Dcert and Vreq ≤ Vcert. However, a requirement combination such as Vreq = 0.1* Vcert and Dc-req ≤ Dcert +0.1*( Dcert – Dc-cert) better reflects the real-world situation commonly found in combinations comprising a rigid truck, converter dolly, and semi-trailer.

E-mail correspondence with regard to the application of provisions in New Zealand standard NZS5446:2007 for tyre scuffing forces to the approval of drawbars for lateral forces under UN R55.

Observations on type-approval and “in-use” requirements under UN R55 and proposal to develop a new Annex that would provide a more coherent approach to evaluating/limiting acceptable in-use stress loads than in the current regulation.