Earthmover, quarry & mining tyres

The core OTR fitment. A loader lives on scrub — turning under load, ramming a face, reversing on rock — so the tread is worked sideways as much as forwards, and the shoulder is usually the first thing to go.

Specify by surface. On concrete, stockpile and sand an L-3 regular-depth rock tread is right and gives the best cost per hour. On blasted rock and quarry floor, go to L-4 deep tread or L-5 extra deep for the cut protection, and accept that the extra rubber runs hotter and limits how far and how fast the machine can travel between faces.

Where a loader tramps a long stockpile road, treat it as haulage rather than loading and check the heat capacity, because a deep-tread loader tyre on a long run is the classic way to destroy a set from the inside.

ADTs cover ground. That makes heat, not cutting, the governing constraint on long hauls: the tyre spends most of the cycle rolling at speed under load, and a deep L-5 tread on a long haul road will destroy itself from the inside.

This is where TKPH has to be calculated rather than assumed. Work out the site figure from the mean tyre load and the average cycle speed across the shift, then compare it against the rated TKPH of the candidate tyre. If the site figure is higher, either change the tyre specification or change the cycle.

ADT loading is also markedly uneven: the rear axles carry the payload and the front axle carries the tractor unit, so the two positions wear and fail differently and should be specified and rotated as separate populations.

Rigid haulers in quarry and mining service carry the highest loads in the sector on the smallest number of tyres. Availability, not price, is normally the constraint: these sizes are manufactured to order in limited volumes worldwide, and lead times move with global mining demand rather than with UK supply.

Plan the replacement rather than reacting to it, and keep good used casings in view. On this class of tyre, repair and retread are a normal part of fleet management rather than a compromise — a sidewall repair on a 27.00R49 is a routine economic decision.

Haul road condition is the largest single variable in the cost per hour. Spillage on the road, tight radii and poorly maintained cambers cause more removals on rigid haulers than tread wear ever does.

Wheeled excavators run on dual or single fitments with very high static loads and almost no rolling distance, so tread wear is rarely what removes them. Sidewall cutting and impact damage are.

Because the machine is often stationary and slewing under full load, the tyre is loaded and unloaded on the same spot repeatedly, and the bead area takes the reaction from the slew. Check for bead area cracking and sidewall zipper damage at inspection.

On a site full of rebar, scrap and blast debris, foam filling is worth costing — the machine is slow, the weight penalty matters less than on a hauler, and the failure being avoided is a lost shift. See our foam filling guide.

Graders need lateral grip against the blade load and a tread that will not tear the surface being finished. The TRA G-2 grader tread — a traction pattern of intermediate depth — is the standard answer, with G-3 where the surface is more abrasive.

The characteristic failure is shoulder and sidewall damage from working close to a kerb or a bank while the blade is loaded sideways. Review the working conditions and fitment when selecting a replacement.

Graders on quarry haul road maintenance work harder than the same machine on a civils job: they spend their day in spilled rock rather than on formed ground.

Underground load-haul-dump machines work in a confined, abrasive, hot environment with no ventilation to speak of and continuous duty. Tyres are consumed by cutting and heat, and a failure underground costs far more in recovery than the tyre is worth.

The specification is normally an extra-deep tread with the maximum practical cut protection, and often a smooth or near-smooth extra-deep variant — the L-5S — which puts the maximum rubber over the crown for machines that need protection more than they need pattern.

Heat is the constraint that catches people out. Ambient temperature underground is already high and the cycle is continuous, so a tyre that would be adequate in a surface quarry at the same load and speed may not be adequate below ground.

Wheel dozers, motor scrapers, water bowsers and support plant on a quarry or mine site. Much of this fleet is still bias, in high ply ratings, because bias casings resist sidewall cutting well and the machines do not do the distance that would justify a radial.

Scraper work is the most punishing loading cycle in earthmoving: the machine is loaded while moving, at speed, over the material it is cutting. Expect impact damage and cut sidewalls rather than even wear, and expect the front and rear positions to have entirely different lives.

Include water bowsers and support vehicles in the tyre maintenance plan. They use the same haul roads and need specifications suited to their loads, speeds and surface conditions.