Whether you’re driving paved roads or navigating uncharted territory in the desert, you can go anywhere with General Tire. With more than 100 years of experience in the tyre industry and as part of Continental – a leading tyre manufacturer based in Germany – General Tire delivers products you can rely on. General Tire lives up to this reputation, and will give you the skills and experience to conquer all types of terrain, and benefit from the legendary performance of the General Grabber 4x4 tyre range.
Whether you’re driving on paved roads or navigating uncharted territory General Tire offers SUV and 4x4 drivers robust and durable tyres for every application. This is one of General Tire’s core competences with its proven American heritage and exceptional performance in all types of terrain.
|4||Differential (Rear Axle)|
In a conventional rear-wheel drive vehicle the drive is transmitted from the gearbox to the rear prop shaft. This, in turn, sends drive to each wheel through the differential.
Four-wheel drive vehicles are typically equipped with one of three drivetrain systems: part-time 4x4, full-time 4x4 or all-wheel drive.
Selectable or part-time four-wheel drive systems allow the driver to choose between two-wheel drive or four-wheel drive, depending on the driving conditions. In 2WD mode, drive is sent to the rear axle only, but in 4WD mode, drive is sent to both the front and rear axle via a transfer case.
A vehicle equipped with full-time 4WD is permanently in 4x4 mode, as typically found on spart utility vehicles (SUVs). Drive is sent to the front and rear prop shafts via a third or centre differential.
In some 4x4 models, a centre diff-lock is provided, which locks the front and rear differentials together to maximise traction on loose surfaces such as gravel roads and rough off-road terrain.
The centre diff must not be locked when driving on hard surfaces or on the road. As the front wheels rotate at different speeds relative to the rear wheels when cornering, it's essential to have the centre diff in the open position. This allows the drive to be sent to the wheels with the least resistance.
|1||Differential (Front Axle)|
|5||Rear Prop Shaft|
|6||Differential (Rear Axle)|
All-wheel drive (AWD) systems are typically used in so-called soft-roader or crossover vehicles which are primarily designed for on-road use. Although they don't have a low-range transfer case, AWD vehicles feature a measure of off-road ability with increased ground clearance and the benefit of added traction for slippery conditions.
In normal on-road use the drive is primarily sent to either the front or rear wheels. When a significant difference between front and rear wheel speeds is detected, the system relies on a viscous coupling to automatically transfer drive to the wheels with more traction.
In some models, the driver can switch from "4x4 Auto" mode, as above, to "4x4 Lock" which locks the centre differential to split the drive evenly between the front and rear axles.
Alternately, electronic systems are used in some vehicles to brake and reduce power to wheels with the least traction, thus directing more drive to wheels with greater grip. Unlike conventional mechanical 4x4 systems, electronic or traction- control based systems require a different driving approach in tricky off-road terrain.
Where reducing power to regain traction is suggested for proper 4x4s, electronic-based systems rely on the steady application of power to maximise the efficacy of the braking and traction control functions.
The primary function of a differential (or “diff”) is to allow wheels to turn at different speeds in corners. When turning, all four wheels on a vehicle follow a slightly different radius – and thus, travel at different speeds. An “open” differential sends drive to the axle with the least resistance.
A differential lock ensures that each side of the diff receives equal amounts of drive – and this can apply to a centre diff-lock, the common rear diff-lock, or even a front diff-lock on certain vehicles. As both wheels are effectively locked together, and rotate at the samespeed, traction on loose or uneven surfaces is maximised.
The diff-lock, which can be fitted on both 4x2 and 4x4 vehicles, should be engaged prior to driving into situations where traction is likely to be lost, but it’s essential to disengage the diff-lock when travelling on hard surfaces, or when cornering.
Besides the conventional gearbox that transmits torque to the driven wheels in normal driving conditions, most 4x4 vehicles rely on a two-speed transfer gearbox for serious off-road driving. This may be engaged by means of a transfer gear lever or, more commonly, via an electronic switch.
However, this should not be used when driving on-road or on hard surfaces.
On part-time 4x4 vehicles, changing to 4x4 involves shifting from 2H to 4H which can often be done on the move with “shift-on-the-fly” systems.
Full-time four-wheel drive vehicles have 4x4 permanently engaged with the option of locking the centre diff for increased stability.
Selecting low-range can only be done when the vehicle is stationary. In low-range, the gearing is reduced to approximately 2:1 depending on the vehicle. This effectively halves the vehicle speed but doubles the torque compared to the high-range ratios.
Low-range should be engaged in difficult conditions where it’s essential to drive at low speeds, including rough or rocky terrain, steep gradients or where maximum torque is required.
Choosing the ideal gear for any particular situation comes with experience, but typically pulling off in second gear is recommended, as first gear low-range is extremely short and could cause unnecessary wheelspin. The accelerator must be applied carefully due to the high-torque nature of the gearing.
Changing gears while traversing an obstacle, or tackling steep gradients, is not recommended, as it could result in a loss of control.
When encountering unknown or difficult sections be sure to conduct a preliminary inspection of the route on foot to determine the best possible lines, and reduce the risk of getting stuck or damaging the vehicle.
The main functions of a vehicle’s suspension are to control the vertical wheel movement and to maintain contact with the ground.
Suspension systems vary depending on the vehicle manufacturer, model and its intended application, with the aim of achieving the ideal compromise between on-road comfort and stability versus good off-road performance – the latter usually measured in suspension articulation.
There are two main types of suspension systems for 4x4 vehicles, comprising independent or solid axle suspensions.
As the name implies, an independent suspension allows each wheel to move independently of the opposite side wheel and is commonly used all-round on SUVs, or on the front axle on light commercial vehicles. This ensures good road holding, comfort, handling and stability due to a low unsprung weight and a lowered engine position for improved centre of gravity.
Although an independent suspension offers excellent wheel travel and axle articulation its design results in variable ground clearance relative to the differential. The wheels rise as they hit a bump, however the diff remains in the same relative position, effectively reducing the ground clearance. This is more likely to result in the vehicle bottoming out over uneven terrain. It is also a complex system with several exposed moving parts that could be prone to damage during extreme off-road driving.
Often referred to as a solid beam, rigid or live axle suspension, this configuration is tried and tested for light, medium and heavy vehicle applications. It is found on the rear of most pick-ups or “bakkies” matched to leaf springs that take the place of the coil springs used in an independent suspension – however coil springs may also be used to provide a smoother ride.
The wheels are connected by means of a solid axle. Accordingly, when one wheel moves up, the opposite wheel moves down, thereby maintaining clearance below the axle over rough ground. While this is an advantage in 4x4 conditions, the weight of the entire axle and diff constantly moving with any bumps leads to a rougher ride compared to an independent suspension.
As all the moving parts are enclosed in the axle casing, they are protected from impact and damage when driving off-road. The solid axle is extremely robust and can handle heavier loads than an independent setup.
The better you know your 4x4, the greater your understanding of its abilities – and yours – when driving off-road. This will enable you to arrive safely and reduce the risk of damaging your vehicle.
It’s essential to understand the following terms, what they mean and how they apply when traversing rugged terrain and tackling obstacles. Remember that all of these measurements will be impacted when tyre pressures are reduced, or the vehicle is heavily laden:
As a fundamental part of off-road driving, it’s essential to know what the maximum angle of attack is for your vehicle when approaching an obstacle, and the maximum departure angle is when exiting the obstacle – the latter often negatively impacted by accessories such as a towbar or tow hitch. The break-over or ramp angle is equally important, and dictates the maximum angle that a vehicle can drive over without the apex of the obstacle touching the chassis or underbody.
The type of terrain you are facing plays an important role in your decision-making. Jagged terrain, for example, poses significant risk to the under- carriage with many opportunities for damage to components located underneath the vehicle.
Off-road driving often involves negotiating water and river crossings. It’s critical that you know what the maximum wading depth of your vehicle is to ensure safe passage without incurring damage.
Wading depth refers to the maximum water depth it is safe to take your vehicle to. It doesn’t only account for the height of your air intake, but also that of the breathers for the axles and gearbox, plus any electronics – hence having a snorkel fitted is unlikely to result in any increase in wading depth.
Be sure to walk the route first and assess the water depth.
Keep in mind that the lowest point on any vehicle is usually the differential, so that should be considered when venturing off-road and, in particular, when trying to avoid obstacles such as rocks and boulders.
This refers to the maximum angle of the gradient that the vehicle can be driven up safely while maintaining safety and traction on all four wheels. The roll-over angle is the point at which a vehicle is likely to topple over when driving on a steep side slope. Both angles will change significantly when the vehicle is heavily loaded – particularly when a roof rack is fitted.
Maintain momentum and traction through the obstacle, especially on cross-over situations. If the engine stalls or the wheels lose traction on an incline, only make use of the foot brake to ensure the vehicle stalls in gear (manual gearboxes). Do not use the clutch.
Identify the reason for the stall or getting stuck by checking your gear selection and for potential obstacles that might be impeding progress.
This requires route planning for optimum entry and exit points.
A very common occurrence on hill climbs is the stalling of the vehicle when the hill becomes too steep. When this occurs the vehicle will be in gear with the engine switched on but stalled.
To recover from this situation you should perform a Hill Stall Recovery rather than just firing up the engine. This is accomplished by following these steps:
As long as you are in reverse gear, this will result in a smooth downhill progression while starting the engine. If you are out of gear during some stage of the take-off or simply start the engine and then select reverse gear it will result in a fast and jerky take-off that could result in a loss of control over the vehicle.
The Hill Stall Recovery does not apply to automatic vehicles as they should never stall, they would just lose forward drive when the hill becomes too steep for the gear they’re in. When this occurs simply place your foot on the brake, select the appropriate gear and gently take your foot off the brake.
Mud comes in various forms, from thick, bottomless clay to the slippery surface mud found in forests. The key is to reduce tyre pressures and select second or third gear low-range to give enough engine speed and momentum, but limit excessive wheelspin.
Before you drive through any mud take the time to look at the terrain and where you need to go. Better to get your shoes a bit dirty than just blasting into it and getting stuck!
There will be times when you will become stuck. The first thing to do is to stop the vehicle. Trying to drive out once already stuck may just dig the vehicle in further. Take some time to work out why you’re stuck. Dig away any mud in front of the wheels and place items such as car mats, or even branches, under the wheels to give you traction.
Don’t try to force the steering wheel in a particular direction, just hold the wheel gently and guide the vehicle in the direction that you want to go. Of course, a diff-lock can help you to get through muddy patches, but as is the case with sand driving, they will tend to force the vehicle to go straight.
Pulling away may also require some assistance in the form of a push or a tow rope. Useful tools to take along are a tyre gauge, compressor, decent tow rope and a spade.
The mud terrain or mud tyre pattern is characterised by large lugs on the tyre with big voids between these lugs. The large lugs provide plenty of bite in low traction conditions while the big voids allow the tyre to clean itself by throwing off mud or other material when rotating.
When driving through demanding terrain avoid the tendency to hold the steering wheel in a death grip – let the wheel move around and gently guide the vehicle. Releasing the wheel slightly allows the wheels to “centre”, ensuring that they are pointing in the right direction. Similarly, use gentle applications of the brakes and accelerator.
Dropping the tyre into a ditch or crack in a rock can put you and your 4x4 in a vulnerable position. Sometimes the vehicle pitches and one or more tyres will be raised off the ground.
Be very deliberate and careful when approaching this challenging section of any trail. Logs can bounce up and catch the undercarriage, so come off these obstacles slowly and carefully. Turn the vehicle at an angle to facilitate the one-tyre-at-a-time approach. Be careful not to allow one of the front tyres and one of the rear tyres to get in the ditch at the same time.
Among the most pertinent considerations with regards driving in sand is utilising the optimum tyre pressure. This is a combination of many things. Your tyres, their construction methods and materials, what your car weighs, how it is loaded and wheel width, all play into the sand-pressure tyre formula with predictable results.
The choice of treadpattern is extremely important to consider during your new tyre decision making process, especially if you’re fitting your 4x4 for an off-road adventure. Loose, dry sand can absorb a great deal of power so the higher gears should be selected while in low-range or lower gear options if you are in high-range.
To begin with, choose a gear that allows the engine to rev slightly high, allowing you a safety margin in the event of deep patches. When you feel wheel-spin beginning, ease off on the accelerator; if you feel that you’re getting stuck, take your foot off the accelerator and coast to a stop. If you can reverse, try and clear the problematic section and either find an alternate route or gain more momentum.
Momentum is key in these conditions, so keep a constant speed in second or third gear. Use your steering wheel to regain lost traction by steering from left to right between the 10 o'clock and 2 o’clock positions to assist traction.
Wherever possible, try to park the vehicle facing downhill as this will make pulling away easier. Sand driving is easier in the early morning due to the effect that the condensation and temperatures have on the sand particles.
You can reduce your tyre pressure as low as 1.0 bar on 4x4 vehicles, however, do bear in mind that any sudden turns may cause the tyre to roll off the rim. If your vehicle is fitted with a diff-lock be very careful when using this in sand as it can cause the vehicle to handle differently, including making tight turns more difficult by forcing the vehicle to go straight.
Avoid turning the steering wheel excessively as the sand builds up on the outside of the front wheels and can suddenly cause the vehicle to turn. Vehicles can easily roll over, even at low speeds.
There will be times when you will become stuck. Take some time to work out why you’re stuck. Dig away any sand in front of the wheels and place items such as car mats, or branches under the wheels to give you traction.
As always, when you’re going off-road take along your tyre gauge and compressor (to re-inflate tyres), a shovel and your trusty tow rope or snatch rope.
Low-range and first gear is the right choice in extremely rocky and rough terrain. environment, using a slow pace in order to react in time to unexpected or hidden obstacles. Using first gear in low-range will allow vehicles to effectively propel themselves, with no input required from the accelerator.
When large drop-offs or ledges are encountered they can be tackled at an angle to allow one wheel at a time to mount the obstacle. Bear in mind how this will affect the position of the vehicle as turning at an angle to a downhill ledge may result in the side rollover angle being reached.
A cross-axle condition exists if you attack a ridge at the wrong angle. This will result in two diagonally opposed wheels losing traction. To recover from this condition and continue, engaging diff-lock will allow the vehicle to overcome the loss of traction. A lower tyre pressure will also aid traction.
Continued use of the same ground can cause rutted roads. As they become more pronounced, wider and deeper ruts can make travel difficult. Approach this situation with caution and do not use aggressive steering to try and overcome these ruts.
The right angle of approach is needed, correctly positioning the vehicle so that one wheel enters the ditch at a time. Attempting to put two wheels into a ditch simultaneously will bring the vehicle to an abrupt stop, and could get you stuck.
Water crossings can be a dangerous and often deceptive challenge. Again, a lot of problems can be avoided by knowing your vehicle. Be aware of how low your air intake is and where breather pipes are situated. As you approach a water crossing, observe the surrounding terrain. Obviously, if the area around the river is rocky there’s a good chance that there will be rocks in the river bed.
Before attempting to cross a river get out of your vehicle and do a visual inspection by walking through the water and assessing the ideal route. Avoid deep water whenever possible, and watch out for hidden gullies and holes as well as fast-flowing water that can easily push the vehicle downstream.
Plan your exit point in advance. When crossing flowing water, ensure the vehicle’s windows are slightly open and that all seatbelts are removed. Cross at an angle that is slightly against the flow – this gives you additional time to respond should the water suddenly start pushing the car.
Never switch the engine off when stationary in water, as this creates a vacuum, resulting in water being sucked into the engine.
Once in the water, maintain a steady speed, avoiding wheel-spin. Drive at a steady pace to create a wave action, or bow wave, in front of the vehicle. This reduces the height of the water behind the front wheel, making it less likely to exceed the maximum wading depth or enter the cabin.
First or second gear is appropriate for running water where there is little mud. Don’t change gear, as the sudden loss of momentum when depressing the clutch will cause the bow wave created by the vehicle to splash over the vehicle.
Take caution though, as excessive speed could result in the radiator fan being forced into the radiator, resulting in critical damage that may leave you stranded. In certain instances, blocking off the radiator grille for the duration of the crossing may be recommended.
Securing a tow rope to the vehicle before it enters the water is highly recommended, as it will make recovery easier, and significantly reduce the time that the vehicle will be in the water, should it get stuck.
If the filter is wet, remove the spark plugs (petrol engines) or glow plugs (diesel engines) and turn the engine over on the starter to remove any water.
Check the engine, gearbox and axle oil as soon as possible after deep water crossings and drain the oil if there’s any sign of water (milky colour). Once you are out of the water apply the brakes gently to remove any water and dirt.
The vehicle manufacturer indicates the correct tyre pressure in the owner’s handbook. These are the inflation pressures that should be used during all normal vehicle use when driving on the road.
Safety is severely compromised by low tyre pressures. Heat build-up is a dangerous side-effect of under-inflation, which will affect vehicle performance, increase fuel consumption, create excessive wear and heat and, potentially lead to a tyre failure.
Confirm the new tyre matches or exceeds existing tyres for load index and speed rating.
Remember that as the aspect ratio of a tyre becomes smaller, the width of the tyre increases.
|Example: 31 x 10.50 R 15 LT|
|31||=||Tyre diameter in inches|
|10.50||=||Tyre width in inches|
|15||=||Rim diameter in inches|
Use the correct bead lubrication for fitment procedure.
After mounting the tyre one should remove the valve core and first inflate the tyre to seat properly.
The tyre will now relax on the rim; deflate the tyre, put the valve core back and inflate it to the recommended inflation pressure.
|SI||Maximum Speed (km/h)|
When venturing off-road it’s essential to have a basic set of recovery gear in the vehicle at all times. No 4x4 adventure should be undertaken alone, with a convoy of at least three vehicles being the minimum recommendation for the safety of all participants, and the ability to assist a vehicle that is stuck or broken down.
Ensure you undergo proper training on the safe operation of all recovery gear before heading off on any journey.
All recovery procedures come with an element of risk. Follow safe procedures when using recovery equipment to minimise injury and/or vehicle damage.
Only use bow shackles for vehicle recovery work and avoid conventional D-type shackles. Alloy bow shackles are much stronger and have a larger inside radius which is useful for attaching straps.
These shackles carry a special rating, and the tension pin will be of a different diameter to that of the shackle body.
It’s important to invest in high-quality vehicle jacking equipment for any off-road driving. This is crucial for replacing a wheel in the event of a puncture, conducting repairs out on the trail, and potentially even being required during a recovery procedure.
Never work beneath a vehicle only supported by a jack. For added safety, place spare wheels under the vehicle or use additional jacks as further supports. Chock the wheels on the ground firmly to prevent the vehicle from moving.
All vehicles can cause irreparable environmental damage, especially to sensitive eco-systems. Something as simple as wheelspin can result in the development of ruts. This may then lead to the creation of new watercourses and later, erosion. Any ruts created should be filled in as best as possible to avoid such potential occurrences.
The topsoil is held together by smaller plants with saplings growing into trees. Their existence dictates the kinds of insect and animal life found in the area – so always keep this in mind when driving off-road.
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