4x4 Commercial Tyre Guide.

Match the tyre to the load, not just the vehicle

A tyre's load index and speed rating state how much weight each tyre can carry and at what sustained speed. When a vehicle regularly runs near its maximum weight — a full tray, a loaded trailer on the tow bar — every tyre needs enough capacity in reserve. Fitting a tyre rated below the vehicle placard, or below the original equipment, is unsafe and can affect an insurance claim.

Light-truck (LT) tyres have stiffer sidewalls and stronger casings than standard passenger (P) tyres. They resist damage on rough ground and hold their shape under load, at the cost of a firmer ride when the vehicle is empty.

• Check the tyre placard (usually on the driver's door jamb or fuel flap) for the specified size, load index and speed rating
• Never go below the specified load rating; moving up is generally fine
• For regular heavy or towing work, LT construction is usually the better choice
• Keep all four tyres to the same type and size unless the vehicle maker says otherwise

Choose a tread pattern that suits where the vehicle actually works

Tread pattern trades off grip away from the bitumen against wet grip, noise and tread life. Most commercial 4x4s spend far more time on sealed and formed roads than the owner expects, so be honest about the real duty cycle.

• Highway terrain (H/T): quiet, long-wearing and strong in the wet — best for vehicles mostly on sealed roads
• All terrain (A/T): a balanced pattern for mixed sealed, gravel and dirt; a common choice for trade and rural fleets
• Mud terrain (M/T): large tread blocks for soft, loose and muddy ground; noisier, shorter tread life and longer wet stopping distances on the road

Pressure, rotation and inspection

Pressure is the single biggest factor in how a commercial tyre wears and how the vehicle carries a load. Run the pressure recommended for the load being carried — many vehicles list a higher figure for a full load than for a light everyday run — and always check it cold, before driving.

Rotating tyres on a regular schedule evens out wear between the driven and non-driven axles. Inspect for uneven wear, cuts, bulges and embedded objects, especially on vehicles working on rough ground.

• Set pressures to the load, using the placard's laden figure when the vehicle is working
• Check pressures cold, including the spare, at least monthly and before long trips
• Rotate on a regular schedule and after any alignment work
• Replace tyres showing sidewall damage, cracking or uneven wear rather than waiting for the tread limit