Michelin X-Crane Tyres Now Capable of 50mph

Michelin’s latest X-Crane tyres now offer an ‘F’ speed rating (50mph) in place of the previous ‘E’ rating (43mph). The move follows technical approval from the European Tyre and Rim Technical Organisation (ETRTO) under recommendation to the Department for Transport, which has granted authorisation for ‘F’ rated tyres with the same load/speed chart used for tyres with an ‘E’ speed index. It also states that for speeds below 40mph, a formal tyre manufacturer agreement is required.

The ‘F’ rated Michelin X-Crane tyres were launched in response to requests from crane manufacturers for a tyre which could meet the high performance of the latest generation cranes, which are capable of speeds in excess of 50mph. Furthermore, legislation announced at the end of 2004 governing the use of mobile cranes on a public highway changed, with a series of new weight and speed restrictions being introduced.

Darren Lindsey, Head of Michelin Earthmover and Industrial Tyres, explained: “Although the new legislation allows speeds of up to 40mph for category C cranes, and permits axle weights of up to 16,500 kg, the tyres are not necessarily capable of operating at the highest load/speed rating.

“The new ‘F’ rated Michelin X-Crane tyres solved this issue in mainland Europe, but the legislation had serious implications for UK operators, which fall under STGO regulations, as it restricted their load carrying capacity. This approval from the ETRTO has overcome this issue, and ensures that operators in the UK can enjoy the same benefits from the ‘F’ rated X-Crane tyre as their counterparts on the continent.”

The restrictions which previously stopped ‘F’ rated tyres from being used at the new weight and speed limits were purely a legal complication, rather than a lack of capability from the tyre. This was caused by there never being a schedule for ‘F’ rated tyres from the ETRTO, which meant that as soon as one was produced it fell under Regulation 54 (which is a United Nations agreement covering the approval of pneumatic tyres for commercial vehicles and their trailers).

This is clearly illustrated by the difference between the 385/95 R 25 170E and 170F tyres. Both tyres have exactly the same dimensions and so should carry the same loads at various speeds but because the ‘F’ rated tyre falls into Regulation 54, it actually carries less load at lower speeds than the ‘E’ rated tyre.
STGO regulations in the UK class mobile cranes under three principal categories, including category A, with axle weights of up to 11,500 kg, category B with axle weights up to 12,500 kg and category C with axle weights up to 16,500 kg. These weight restrictions are aligned with speed restrictions, with motorway limits set at 60 mph for category A, 50 mph for category B and 40 mph for category C.

The table gives the maximum permitted speed related to vehicle category, axle load and tyre size 2. This table is only valid and may only be applied in connection with the instruction manual.

Regulations state that mobile cranes fitted with the new ‘F’ rated tyres and the existing ‘E’ rated tyres must feature a self-adhesive sign on the dashboard giving tyre related speeds for each tyre dimension listed.