Case Study: OTR Tires for a Nigerian Mining Contractor
A Nigerian mining contractor sourcing OTR tires for haul trucks and wheel loaders on unsealed pit roads. The case sets out the four data points that decided the shipment: the failure mode behind downtime, the SONCAP clearance sequence, the exact size and rating convention on the rim, and the loading plan with its spare ratio.
OTR tire supply into Nigeria is usually decided by two documents nobody in a showroom ever asks about: the specification sheet and the SONCAP file. This case follows a mid-sized mining contractor working the country's solid-mineral belt, running haul trucks and wheel loaders on unsealed pit roads and stockpile yards, and the sequence of decisions that had to be closed before a container could be booked.
Nothing below is a product catalogue. It is the order in which the requirement was pinned down, and the data each step depended on.
The enquiry data sheet: what has to be on the table first
The first version of this enquiry read "OTR tires for mining, please quote". That is not quotable. Before a factory in Huangshi can confirm availability, the sheet has to carry the fields below, because each one changes either the construction, the load capacity, or the customs line item.
| Field | What the buyer supplies | Why the supplier cannot assume it |
|---|---|---|
| Size and construction | e.g. 18.00-25 or an R-notation equivalent | The same nominal size in bias and radial carries different load and speed limits |
| Rating | Ply rating (bias) or star rating (radial) | Rating sets the load per tire at a given speed; under-rating is the most common cause of sidewall failure |
| Rim and flange | Rim diameter, flange type, dual spacing | A tire that fits the hub but not the flange will run hot or foul the dual gap |
| Machine and axle position | Model, front or rear, loaded or empty weight split | Front and rear axles on the same truck see different load and heat duty |
| Operating TKPH | Ton-kilometres per hour from cycle length and payload | The single figure that decides whether a heat-resistant compound is mandatory |
| Quantity and batch | Units per shipment, and whether trial quantities | Determines whether the order runs as a small trial batch or a full container build |
Punctures, cuts, and where the downtime actually comes from
On pit roads the failure is rarely a clean wear-out. It is a sidewall cut from blasted rock, a tread puncture from a rebar or a bucket tooth, or a heat failure after weeks of under-inflation on a long loaded haul. Each has a different fix, and mixing them up leads buyers to order a heavier tire than the machine can actually use.
The contractor's own records pointed to cut and impact damage rather than tread wear, which shifted the requirement toward a deeper, more cut-resistant tread and a tougher sidewall, not toward a longer-wearing compound. That distinction also kept the load rating unchanged: adding cut protection by going to a thicker, stiffer casing would have raised heat build-up on the haul road, which is the opposite of what a hot-climate site needs.
Downtime cost is what makes this argument commercial rather than technical. A single tire change on a haul truck stops the unit, and on a short cycle it can cost a full shift. That is why the discussion moved from unit price to the number of hours a tire actually delivers on that specific road — and why the compound, not the price list, was the first thing settled.
SONCAP: the clearance step that sets the shipment date
Tyres sit on Nigeria's regulated product list, so the container cannot clear on a commercial invoice alone. The sequence that governed this shipment ran as follows, and it is worth building backwards from the vessel date because the paperwork, not production, is normally the critical path.
- Form M opened through the importer's bank, with the proforma invoice as the basis.
- Product Certificate — issued against the product and the factory, not against a single container. It is the long lead item, and it is why a first-time supplier should start the file before the order is final.
- SONCAP Certificate per shipment, issued after inspection and testing of the consignment against the registered product.
- PAAR from the customs trade portal, which requires the SONCAP certificate to be in place before the entry can be lodged.
Practically, this means the shipping documents and the tire specification have to agree exactly. A size or rating that differs between the proforma invoice, the packing list and the certificate will surface at the port, not at the factory. The tires in this case came from the Aolais plant in Huangshi, which already holds GCC, SASO, SONCAP and DOT certification — so the certificate route was a document-matching exercise rather than a new approval cycle.
Size and rating: five fields that must match the rim
The size line on an OTR tire is a compressed specification, and reading it wrong is expensive. The conventions that mattered here:
| Notation | Construction | Rating basis | What it governs |
|---|---|---|---|
| 18.00-25 | Bias | Ply rating | Load per tire at a stated speed; stiffer casing, more heat |
| 18.00R25 | Radial | Star rating | Load per tire with more deflection and cooler running |
| Load index / speed symbol | Both | Supplementary | Absolute limit; not a substitute for the site duty cycle |
Two more fields caused back-and-forth. First, the rim: a 25-inch tire needs the correct flange profile and, on dual fitment, the right spacing so the sidewalls do not rub when loaded. Second, the star rating on a radial is not interchangeable with a ply rating on a bias tire — a number that looks higher on paper can mean less load capacity in practice. We confirmed the rim, the flange and the axle load split with the contractor's workshop before releasing the order, which removed the usual first-shipment risk of a tire that fits but cannot be run at rated load.
Loading, spare ratio, and the mixed container
OTR tires load badly on their own. They are heavy, they do not stack neatly, and large sizes need cradles or vertical standing rather than flat compression. Because this contractor also buys brake shoes and filters, the shipment was built as a mixed container: tires on the floor and in the end bay, brake assemblies and filters in cartons filling the remaining volume, with the axle-end loads calculated so nothing shifted in transit.
Spare ratio was set as a planning figure, not a promise. For haul trucks on abrasive pit roads, the working range is roughly one spare per four to six units in service; for loaders in stockpile work, one per six to eight is usually enough. The ratio rises with haul distance, with the proportion of blasted rock on the road, and with how far the workshop is from the nearest tire stock. It falls when the site can re-section a casing locally. We wrote the ratio into the packing list so the next order could be sized against actual consumption instead of guesswork.
What the case settles, and what it does not
The measurable gain was in the file, not in a headline: specification confirmed against the rim and axle load before production, certificate route matched to the invoice line by line, and a loading plan that carried three product families in one container. We do not publish client tonnage, fleet counts or cost savings — those belong to the operator.
For buyers running the same calculation, the workable order is: pin the failure mode, then the size and rating, then the certification file, then the container. Sending all four together is what turns an enquiry into a shipment date.
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