Michelin Demonstrates Value of Premium Off-Road Tyres

Michelin is holding the Bath Stone Group as an example of the value of opting for quality, premium tyres. According to the tyre maker, the Bath Stone Group is benefitting from a change in tyre policy that has seen tyre longevity on its underground loader shovels rise by 800 per cent, thereby significantly increasing productivity at its Stoke Hill Mine.

The new tyre policy, introduced in the second half of 2009, relates specifically to two Wagner ST2D underground loader shovels used at the mine. Each of these two loader shovels is in operation for approximately 20-25 hours a week, clearing waste inside the mine on a very abrasive working surface. This harsh environment means the machines require sturdy tyres to avoid punctures and rapid wear, which in turn can lead to machine downtime and waste build-up, and subsequently stop the mining operation. Previously, the units were fitted with the Chinese produced Protector Tyres brand; the change in tyre policy has seen a switch to Michelin X-Mine D2 radial tyres.

The Protector tyres used on the machines until August 2009 were lasting between 50-250 hours, with an average life of 10 working days – and in several cases a new tyre was completely worn out after just one day. “There were constant punctures, and when we were really driving the machines hard, the Protector tyres were flexing, distorting and overheating,” reported Bath Stone Group training officer Matt Johnston. “We were using these tyres because we didn’t realise there was a better alternative. The constant delay with bringing machines to the surface for new tyres was a major disruption to the operation.

“Then we bought a pair of reconditioned machines from France – and the Michelin X-Mine D2 radial tyres on them were simply a world apart,” Johnston added. “We’d bought them part-worn at 250 hours – and they lasted 3,000 hours.” Johnston contacted Michelin, and a representative was sent to discuss Bath Stone’s requirements and inspect the mine’s working surface and machinery. The Michelin representative confirmed the X-Mine D2’s suitability for the Stoke Hill Mine’s operation conditions, and presented a proposal highlighting the difference in productivity and economy between the two tyre brands.

According to Michelin, conservative projections showed that the Michelin X-Mine D2 radial tyres were likely to achieve at least 2,000 hours in operation, in comparison to the Protectors’ 250.  Although the cost of fitting the loader shovels with Michelin rubber was three times more than with Protector tyres, the actual cost per 100 hours was £62.50 per tyre versus £160 for the Protector tyres. This meant an estimated saving of £1,185 per tyre per 1,500 hours.

“Switching to Michelin tyres was the best thing we ever did,” commented Johnston. “It’s saved us money, time and stress. They’ve been lasting even longer than their projected life-span and we haven’t had a single puncture since the changeover. The visit from Michelin’s local earthmover account manager has transformed our operation.”

Michelin says its X-Mine D2 tyres are designed with a deep tread and damage-resistant buttressed shoulders and sidewalls for increased productivity. Their longevity is explained by their multiple steel belts, cut-resistant rubber compounds and heavy-duty casing, while the radial design protects machine components and makes for a smooth, comfortable ride.

Stoke Hill Mine is situated on a site which has been quarried for its famous oolitic limestone since Roman times. Stoke Ground is a variety of Bath Stone regularly specified by English Heritage, The National Trust and The Royal Household. The Bath Stone Group has provided material for Bath’s new Southgate Shopping Centre, Bristol Temple Meads Station and Pembroke College, Cambridge. The mine itself, which dates back to Victorian times, goes one kilometre underground and is worked by 15 members of staff who operate the various machines needed to produce the 6,000 cubic metres of stone mined there annually.