Quick answer
Choose mining OTR tyres in four steps: confirm the exact size from the sidewall, pick the tread code for the job (E for earthmovers and dump trucks, L for loaders, with 3 for traction, 4 for rock and 5 for extra-deep tread), choose bias or radial construction to suit speed and haul distance, and match the ply rating or load star to your payload. Then keep pressures correct, because inflation is the biggest single factor in OTR tyre life.
What "OTR" means
OTR stands for off-the-road. These are tyres for machines that work on mine sites, quarries and construction sites rather than public roads: wheel loaders, articulated and rigid dump trucks, graders, dozers on wheels and telehandlers. They carry huge loads at low speed on rock, mud and gravel, so they are built very differently from truck tyres.
Step 1: Confirm the size
OTR sizes are written in two main ways:
- Bias sizes such as 23.5-25: 23.5 inches wide, for a 25-inch rim. The dash means bias (cross-ply) construction.
- Radial sizes such as 23.5R25 or 1400R24: the R means radial.
Read the full size and any markings from the sidewall of the tyre you are replacing. These are the sizes mines and contractors in Zimbabwe ask us for most:
| Size | Typical machines |
|---|---|
| 17.5-25, 20.5-25 | Smaller wheel loaders, compact dump trucks |
| 23.5-25, 23.5R25 | Medium wheel loaders and articulated dump trucks (ADTs) |
| 26.5-25, 29.5-25 | Large wheel loaders and ADTs |
| 18.00-25 | Rigid dump trucks, port and quarry equipment |
| 18.00-33 | Rigid dump trucks in the 35 to 40 tonne class |
| 21.00-35 | Rigid dump trucks around 60 tonnes |
| 14.00-24, 12.00-24, 1400R24 | Graders |
For loader tyres specifically, see our 23.5-25 loader tyre guide.
Step 2: Pick the tread code
OTR tyres carry an industry code that tells you what they are designed for. The letter is the machine type and the number is the tread type.
| Code | Designed for | Use it when |
|---|---|---|
| E-3 | Earthmover, traction tread | Dump trucks on general haul roads and mixed ground |
| E-4 | Earthmover, rock tread | Dump trucks on rocky haul roads where cuts are the main risk |
| L-3 | Loader, traction tread | Loaders in soil, sand and general earthmoving |
| L-5 | Loader, extra-deep rock tread | Loaders at the face in quarries and hard-rock mines |
| L-5S | Loader, extra-deep smooth tread | Very severe rock and underground work, where a smooth tread resists cutting |
| G-2 | Grader, traction tread | Graders maintaining haul roads |
The deeper the tread (3 to 4 to 5), the more rubber there is to absorb cuts, but the more heat a tyre builds if it travels long distances. That leads to the next choice.
Step 3: Bias or radial?
| Bias (e.g. 23.5-25) | Radial (e.g. 23.5R25) | |
|---|---|---|
| Sidewall | Stiff, very resistant to sidewall cuts | Flexible, gives a larger, flatter footprint |
| Heat build-up | Higher on long, fast hauls | Lower, so better for longer haul cycles |
| Traction and ride | Good | Better grip and a smoother ride for the operator |
| Purchase price | Usually lower | Usually higher, often lower cost per hour |
| Best for | Short loading cycles, rough sites, sidewall-cut risk | Longer haul distances, higher speeds, high-hour machines |
As a rule of thumb, loaders working short cycles in rock often do well on bias L-5 tyres, while dump trucks hauling longer distances benefit from radials. Never mix bias and radial tyres on the same axle.
Step 4: Match the load rating
Bias OTR tyres show a ply rating, such as 16PR, 20PR or 24PR. Radial OTR tyres usually show stars (one, two or three). Both describe how much load the tyre can carry at a given pressure. Work out the machine's operating weight plus payload, see how it splits between front and rear axles, and choose a rating that covers the heaviest axle with a margin. A loader's front axle carries far more weight than its rear when the bucket is full.
Pressure: the biggest factor in tyre life
Underinflation is the most common cause of early OTR tyre failure. It makes the casing flex and overheat, and it exposes the sidewall to cuts. Overinflation makes tyres hard and more likely to be cut or to impact-break on rock.
- Set pressure from the tyre maker's load and inflation table for your machine and load.
- Check cold, at the start of each shift.
- Inflate large OTR tyres in a safety cage or with a clip-on chuck and remote gauge, standing clear of the sidewall.
- Consider nitrogen on large tyres, which reduces pressure loss and the risk of fire from heat.
We explain more in how to read tyre size and load ratings.
Site habits that save tyres
- Keep haul roads and loading areas clean. Spilled rock is the main cause of cuts. A grader and a clean-up loader pay for themselves in tyres.
- Avoid spinning wheels when the bucket hits the pile. Spin cuts the tread on sharp rock.
- Watch speed and haul length. Running too fast or too far for the tyre's construction overheats it.
- Inspect daily for cuts, embedded rock and damaged valves.
- Keep records of hours and causes of removal, so you buy the right tyre next time.
Primex and Galaxy OTR tyres from Proclassic
Proclassic Tyres supplies Primex and Galaxy mining and OTR tyres in E-3, E-4, L-5 and L-5S treads, in bias and radial construction, for loaders, dump trucks and graders. We serve mines and contractors from Harare and Mutare and deliver to sites across Zimbabwe. Send us the size, the machine and how it works, and we will recommend the right tyre and confirm stock and price. See all sizes on our mining tyres page.
Get a price on WhatsApp
Send us these four details and we will reply with stock and today’s price:
- Tyre size, from the sidewall
- Quantity
- Vehicle or equipment, make and model
- Delivery location, or collect in Harare or Mutare
Or call +263 716 194 485 · info@proclassicgroup.com