Choose the right 4x4 tyre

There's a BFGoodrich 4x4 tyre for every driver.

BFGoodrich recommends that you fit four identical tyres on 4x4 vehicles (the same brand, with the same tread pattern and same load and speed ratings), and that you follow the car manufacturer's recommendations.

4x4 tyres are grouped into different categories based on the type of vehicle and terrain they're designed for.

4x4 road tyre: for 4x4 cars

• Responsive and extremely accurate on corners and straights
• Designed for use on motorways and in urban areas

Mixed tyre: for SUV-style 4x4 vehicles

• Very rugged tread pattern and sharp design
• Reinforced tread patterns and sidewalls
• Versatile: performs equally well on-road and off-road

"Off-road" all-terrain tyre: for off-roading
and hill-climbing

• Wide tread blocks
• Very high rubber ratio (50%)
• High tread depth: 13 to 17 mm
• Reinforced tread patterns and sidewalls
• Excellent off-road performance

CHANGING TYRE DIMENSIONS

Why would I want to do this?

Some 4x4 drivers may want to fit tyres of different sizes when changing the way a vehicle is used, improve its performance or simply to alter the vehicle's appearance.

Bear in mind that the UK Highway Code applies in full to 4x4 vehicles and you must always follow its rules when making size changes.

Precautions to take

BFGoodrich recommends you follow this advice before making any changes to the size of your tyres:

• The load index must be greater than or equal to the index of the original tyre and must be suitable for the maximum load per vehicle axle.
• For tyres not marked M+S, the speed rating must be greater than or equal to the rating of the original tyre. For tyres marked M+S, the speed rating can be lower, provided you display the label indicating the new speed rating inside the vehicle.
• The vehicle must be fitted with four identical tyres (same brand, same size, same tread pattern, same load and speed ratings, and same usage category) in order to avoid any mechanical issues with the transmission and ensure maximum performance.
• Follow the car manufacturer's recommendations at all times.
• Check that the new tyres are not touching any mechanical components or body parts.
  Furthermore, the tyres must not extend beyond the 4x4 vehicle's wings.
• Ensure that the wheel is compatible with the new tyre dimension.
• Seek the advice of a professional before making any modifications; there are always rules and regulations to comply with when changing a vehicle's dimensions.

4X4 TYRE MARKINGS

The sidewalls of 4x4 tyres feature specific dimensions and markings.

TYPES OF SIZE MARKINGS

Metric system

Imperial system

Flotation system

SPECIFIC MARKINGS

• T/A: Traction Advantage
• KO: Key benefit for mixed use
• KM: Key benefit for mud
• M+S: MUD and SNOW: Suited for driving in mud and snow; found on most 4x4 tyres
• P: PASSENGER: US marking indicating that the tyre is suited for touring vehicles
• LT: LIGHT TRUCK: US marking indicating that the tyre is suited for light trucks
• REINF/Reinforced or XL/ExtraLoad: Indicates that the load index exceeds the standard version

4x4 driving tips

Want to become an off-road pro? Then learn from the 4x4 experts. BFGoodrich has won more than 200 titles in rallies and cross-country races like the Baja 1000 and Dakar.
Off-road driving can be fun - but it's a completely different kind of driving.
So it's worth learning some basic techniques before you venture off the beaten track - to help you avoid getting stuck in any difficult situations.

CROSSING BOGS

Before you enter a bog, stop to:

• study the terrain and determine the best path;
• remove any pieces of wood;
• fasten the straps at the front and back;
• if needed, reduce the tyre pressure to 1.5 bars.

To proceed across the bog:

• use the axle differential lock;
• change into second or third gear;
• maintain a constant acceleration;
• reverse hard to regain grip if the vehicle is bogged down as far as the axle and won't move forward.

After exiting the bog:

• clean the tyres and wheels;
• re-inflate the tyres to normal pressure.

FORDING

Before fording a river, stop to:

• investigate the ford and identify any holes, stones, trunks, etc.;
• determine the best path and an exit point;
• check the vehicle is waterproof;
• deflate the tyres to 1.5 bar.

To ford the river:

• enter the water gently at a constant speed;
• if the engine stalls in the middle of the stream, do not restart the vehicle.
  This may cause water to be sucked in through the exhaust pipe or allow air into the engine.

Once over the ford:

• re-inflate the tyres to normal pressure;
• check under the vehicle to remove any branches or grass.

CROSSING BRIDGES

Before you start, stop to:

• study the terrain;
• lock the differentials.

To move forward:

• change into second gear, if on flat or sloping ground;
• change into first gear and brake gently without locking the wheels, if driving downhill;
• if you get stuck, reverse back and try a different path.

DRIVING ON A SLOPE

To climb a slope:

• lock the differentials;
• attack the climb in first or second gear;
• if you get stuck, brake hard by "standing on the brakes" - when the engine stalls, disengage the clutch and put the vehicle into reverse;
• restart the engine with the clutch engaged and drive back down using the handbrake.

To descend a slope:

• approach the slope in first gear;
• lock the centre differential;
• never disengage the clutch;
• use the handbrake to control your descent;
• if the slope is very steep, brake to assist the handbrake and advance cm by cm;
• if the vehicle skids, press gently on the accelerator to regain grip.

CLIMBING OR DESCENDING A STEP

• if it's a step up 50 cm high, attack it head-on; if it's any higher, approach it at a 45° angle;
• if it's a step down, always approach it head-on;
• engage first gear;
• press the front wheels against the step and come to a stop;
• accelerate to get the front wheels over;
• press the rear wheels against the step;
• accelerate to get the rear wheels over;
• for a step down, control your descent with the brake and advance cm by cm.

CLIMBING A HILL

Before you start, stop to:

• assess the slope and identify any obstacles that might make the slope steeper/increase the risk of tipping (do not rely on the clinometer);
• plan your path and exit zone;
• deflate the tyres, but not too much to avoid tyre roll-off.

To climb the hill:

• avoid braking;
• never disengage the clutch;
• do not use the differential lock;
• attack the slope in first gear;
• drive on to the slope with the front wheels pointed slightly uphill, then move forward with crab-like movements;
• if the vehicle drifts, immediately point the front wheels towards the foot of the slope;
• if the vehicle tips, turn the front wheels towards the foot of the slope and begin to descend.

After, stop to:

• re-inflate your tyres to the normal pressure.

GETTING OVER A DITCH OR BANK

• approach the ditch at a 45° angle;
• plan a fairly wide exit zone;
• lock the differentials;
• cross the ditch with minimum throttle in first gear;
• if you get stuck with crossed axles, reverse and try again with a different path;
• once well-positioned and stable, tap the accelerator to move forward;
• release the accelerator once the rear wheels are across.

Changing your tyres

Of course, tyres don't last forever. The two main reasons for tyre changes are tread wear and tyre damage.

IN FOURS OR TWOS?

Ideally, the four wheels of a vehicle should be fitted with identical or at least similar tyres (in twos).

Tyre advice and tips:

• always change your tyres in twos or fours: it is essential that the tyres on a single axle are absolutely identical, i.e. the same brand, same tread pattern, same dimensions and same ratings (speed and load);
• always try to stick to the dimensions approved by the vehicle manufacturer (keep modifications to a minimum, or seek professional assistance);
• always fit the newest tyres to the rear axle to reduce any loss in grip, whether it is a two or four-wheel-drive vehicle or rear or front-wheel-drive vehicle. Grip losses are very difficult to control at the rear.

BFGoodrich strongly recommends that you comply with the sizes approved by the vehicle manufacturer. However, if you do decide to change the size of the tyres, it is vital that you seek the assistance of a professional.

WEAR, PUNCTURE, REPAIR

It is strongly advised that you check the condition of your tyres at least once a week. Additionally, once a month, check their pressure, groove depth, and whether they are showing signs of sidewall damage or any other signs or wear. If you are in any doubt, do not hesitate to contact a professional to confirm your tyres are roadworthy.

Five reasons to change your tyres

While in some instances a tyre can be repaired, it must be thoroughly checked by a professional first; only a professional can confirm that it has not sustained any internal damage. A tyre must also be removed so that its condition can be judged accurately.

1 - PUNCTURED TYRES

If punctured, your tyre must be examined by a professional to ensure that the inner tube has not sustained any damage that makes it irreparable.

2 - LEGAL WEAR LIMIT REACHED

The UK Highway Code states:

• "The legal minimum tread depth for cars is 1.6 millimetre. This 1.6 mm should be in a continuous band throughout the central three-quarters of the tread width, throughout the whole of the circumference."

3 - SIGNS OF AGEING

How long tyres can be used is difficult to specify and does not depend on the date of manufacture. Tyres that have not been used much or at all can also show signs of ageing. Lots of factors affect the lifespan of tyres, including weather conditions, storage and usage, load, speed, inflation pressure, maintenance, etc. Each of these can considerably alter the expected lifespan of a tyre.

4 - DAMAGED TYRE

A kerb, pothole or blunt instrument can do serious damage to a tyre. Any perforations, cuts or distortions must be examined carefully by a professional mechanic who will confirm whether the tyre has sustained any internal damage and if it can be repaired. As a general rule, and for your own safety, never drive with a damaged or flat tyre without consulting a professional first.

5 - ABNORMAL WEAR

Abnormal tread wear - which is located in patches, in the centre or on the shoulders - is often a sign of a mechanical problem such as misalignment or a balancing, suspension or transmission issue. It can also be the result of unsuitable tyre pressure. Contact a professional if you notice the slightest abnormality.

Tyre structure

A tyre with a radial casing is made up of six main parts.