From 1 January, it will be a requirement under the law to have such a sticker on the rear of all trailers and vehicles with an unladen weight of 3.5 tonnes.
The 30 mph speed limit will apply across the Island for the affected vehicles.
Until autumn last year, all vehicles with an unladen weight of 2.5 tonnes or more were restricted to 30 mph. However, in October the law was changed and now the speed limit applies to vehicles with an unladen weight of 3.5 tonnes or more.
A spokesman for Transport and Technical Services said that the limit was now consistent with driving licence categories.