Trailer Speed Symbols
The SPEED SYMBOL indicates the speed at which the tyre can carry a load corresponding to its Load Index under service conditions specified by the tyre manufacturer. For caravans and light trailers see conditions specified by E.T.R.O 1991, passenger car tyres section 13, reproduced below.
||Maximum car speed for which tyre is suitable
E.T.R.T.O. 1991 - Section 13 - Caravans & Trailers:
An increase of 10% over the load capacity quoted in the tables is permitted when tyres are fitted to caravans and light trailers with a maximum operating speed up to 100 km/h. (60 m.p.h.). The basic inflation pressure should be increased by 3 p.s.i. / 0.2 bar.
This 10% bonus loading is widely used in the U.K. light trailer industry, but should only be used on trailers that are to be sold within the U.K. The caravan industry in the U.K. tends to ignore this bonus loading and use loadings at 130 km/h / 81 m.p.h.