As truck ownership has increased, so has the amount of off-highway recreation. There is no special license required to drive off-road, even though there are many different techniques and practices involved. There does exist an often unspoken etiquette that is practiced by old-school four-wheelers, which developed not just so that everyone can get along on the trail, but, primarily, for safety considerations.
With the availability of trail-ready 4x4’s, both in the traditional truck mold and outside of it, the slow and steady progression of four-wheeling initiation through involvement and camaraderie has been bypassed. The honor-by-association process misses the chance to be taught to the enthusiastic guy who just bought his first real 4x4.
Responsible 4-wheeling is about finesse. Other features and driving techniques assist in the overall safety of your off-road outing, but finesse is the first and most important portion of your driving repertoire to acquire.
Here are some hints to help you out in this area.
- It’s important always to drive within your ability. There are times when in soft sand, like beaches and washes, speed needs to be moderate and flotation through mud and snow needs to be kept up, hence “within your ability.” Usually taking your time on the trail will allow you to pick a smooth path and allow you time to react to the varieties of terrain you can encounter like moving rocks and logs under the tyres. If you have a ground clearance deficiency, going slow helps here, in that, if you do hit a rock with the differential or other rock grabber, it will usually stop the vehicle on impact or you will lightly scrape over it. If you were going too fast and hit a rock or other obstacle, it could knock a hole in the oil pan, differential, or even knock off the oil filter.
- Avoid surprises by surveying the road ahead before you encounter it. Make sure the trail goes beyond the obstacle, doesn't become a bottomless quagmire, has no back side to the hill (cliff?) or just plain ends. You can get a good idea where to place your tyres and the differentials to have a plan of approach. Follow through to beyond the obstacle.
- Driving diagonally = Rollover. Always drive straight down hills or steep terrain. Know your approach and departure angles, the bumper to tyre distance. Some trails will require off-camber driving. In situations like this it’s best to go slow, keeping the tyres in the tracks. Make every attempt to avoid losing attention and ascending up a rock or stump on the up side of the hill. Trucks will tend to slide sideways before rolling over – the tyres will slip sideways a little. Stop if the slide puts you off the edge of the track. If it is clear downhill and a rollover is imminent, immediately turn the vehicle into the slide and drive it down. If that is not an option, and you are going over, turn the vehicle off and hold on to your seat-bottom while hoping that the seat belt works properly.
- Reducing tire pressure will increase traction on gravel and sand. For most 4-wheeling purposes, a tire pressure of 18 to 20psi will be adequate. Highway pressure is another consideration altogether. The tyre is marked on the side, i.e., 50psi at 3300 pounds. In essence, that one tyre could hold my Defender up. Depending on the weight of the loaded vehicle and the size of tyre, a tyre pressure of between 28 and 35psi works in most on-highway applications. Never overlook the importance of reading the manufacturer’s label. The air pressure difference between the front and rear is due to the tyre and auto manufacturers’ experimentation for over/under steer and load variances.
- Cross ditches or logs at an angle so that one wheel at a time goes over the obstacle; the other three help the one wheel to climb over. Dropping the tyre into a ditch or crack in a rock can put you and your truck in a vulnerable position. Sometimes the vehicle pitches and one or more tyres will catch air. 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.
One of the most crucial aspects to off-roading is understanding the absolute importance of tyre pressure. Among the most pertinent tyre pressure considerations in regards to summer off-roading is utilizing optimum sand tyre pressure. Optimum sand tyre pressure is a combination of many things, of which truck-owner’s myths are least productive. However, 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. Why low pressure works, and how to determine your best sand pressure, follows:
It’s a simple fact, which some die-hard truckers still deny, the bigger the footprint, the softer the stuff you can travel in. Boiled down, it’s nothing more than a fact of nature. For those who say skinny, hard tyres are better for snow, mud or whatever, please tell me why they don’t use ten-speed bicycle-type tyres on snowmobiles? Sand rail people and mud boggers know big feet work better as well. With that out of the way, let’s take a look at tyre pressure and footprints.
The choice of tread pattern, otherwise known as your tyre’s footprint, is extremely important to consider during your new tyre decision making process, and especially so if your are fitting your truck for an off-road adventure. Tread pattern should be chosen based on the intended use of your truck. The most popular tread pattern for all around off-road use is a mud terrain pattern.
The mud terrain or mud tyre pattern is characterized 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 spinning, thus providing a good bite on every rotation of the tyre. These tyres are also very popular for rock crawling as the large lugs can provide a way of gripping and pulling the tyres up and over irregular rocky edges where a smoother pattern would just spin. The biggest disadvantage of these patterns is that they run rough and loud on the highway. To reduce this problem; choose a tyre with irregular or asymmetric spacing of the lugs and voids to reduce harmonic vibration at highway speeds. There are also situations such as light powdery snow or sand where an all-terrain pattern would be better.
The general purpose all terrain tyre generally has an interlocked tread pattern with siping (small cuts) on the tread blocks. The voids in these tyres are usually much smaller than those on tyres designed for use in the mud. The more dense pattern of blocks and smaller voids make these tyres more quiet on the street. It also increases the surface area of the tread which gives the tyre improved flotation on surfaces such as light powdery snow or sand. The increased siping can be important in snow were it is the number of edges, even quite small edges, biting into the snow that provides the traction. The downside is that the smaller voids cannot clean themselves as easily of packed mud or slush. If these voids fill up with mud the tyre loses much of its bite and traction is lost.
A variety of manufacturers also offer a family of tires sometimes called trail tyres or some similar name. These are most often tyres designed for use on light trucks or sport utility vehicles which see most of their use on the street. They will generally be quieter, get better gas mileage and last longer than either of the other off-road patterns. The tread patterns are designed to provide significantly improved comfort or performance on the street which can sometimes compromise off-road capability. Fortunately this is the limit to which most of their intended market are likely to take them.
Common 4x4 Driving Techniques
The following techniques are common to all types of terrain. Techniques for particular types of terrain are mentioned under the different terrain headings.
When driving off road, it is important not to place your thumbs on the inside of the steering wheel. When driving over any large ruts or potholes, the wheel could suddenly turn. This may result in the thumb being bruised or even dislocated if it is left inside the rim. Remembering to leave your thumbs on the outside of the steering wheel is a very easy skill to acquire and should become second nature to you. With power steering fitted to most 4Wheel drives these days, this technique is not as critical as the power steering unit dampens out sudden steering wheel movements as well as steering stabilizers. Owners of non-power steering vehicles will have undoubtedly experienced at some time the force at which the steering wheel turns when hitting an obstruction.
It is important to know the position of your front and rear differentials as they are usually the lowest ground clearance point of your vehicle. Similarly, any other low ground clearance points should be noted e.g. exhaust, spare tyre etc. When a large rock or other obstacle is on a track that you must drive over, you should ensure you avoid driving directly over it with the lowest ground clearance point of your vehicle.
When using the vehicle’s brakes hard, your vehicle’s front suspension compresses and you 'use up' most of its suspension travel, When braking sharply to avoid an obstacle e.g. pot hole or rut, and you cannot stop in time, release the brake pedal just prior to hitting the obstacle. This will allow the front suspension to return to its normal height and give more suspension travel when hitting the obstacle.
A four wheel drive vehicle cannot be treated like a normal car when cornering. The 4WD will roll over much easier than a car while cornering if they are taken too fast, due to the higher center of gravity. This applies to gravel and paved roads equally. Although a four wheel drive vehicle generally has better traction on gravel than a car, when safe cornering speeds are exceeded the four wheel drive will tend to roll earlier than a car.
Member of SONOTA (South African National Offroad Trainers Association)