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All Terrain (AT) Tyres

When you are looking for a compromise between off-road capability and good on-road manners, an All-Terrain (AT) tyre is the way to go. These tyres offer good versatility by offering capability on a wide variety of surface types, from dry sealed roads to dirt tracks and fair mud play. All in all, AT tyres are more robust than HT tyres and are suited to roughly 50% off-road use.
Article By: ExplorOz Team - Damian    Updated: 10 Jun 2008
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 AT Tyre Overview

The AT (All-Terrain) tyre has been around for many years and is still the preferred choice for 4WD owners who wants to use their vehicle both on and off road. Unlike HT (Highway Terrain) tyres, the extra void in the pattern improves grip on unsealed surfaces and aids clearing of mud and dirt from the tread surface.

Considerable advances in technologies mean these tyres can now be used for everyday driving on the road, with acceptable level of grip and ride comfort. Better tyre designs have improved traction, greater gravel wear resistance and decreased stone retention. Bruise and puncture resistance is supported by multiple full-width steel belts, whilst giving precise steering response and cornering control. Many manufacturers are also using harder tread compounds which provide maximum longevity. This has lead to claims from manufacturers of over 130,000km before the tyres need replacing.
Bridgestone D694
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Bridgestone D694

For the best of both worlds, it’s hard to go past the Bridgestone D694 all-terrain tyre. The so-called “Desert Dueller” is now legendary for its ability to master on and off-road conditions, making it a sound choice for the city dweller that enjoys regular off-road adventures.

Suitable for light truck and recreational vehicles, the D694 offers a block-tread pattern that minimises tread movement to decrease noise and improve handling. Its dual steel-belt construction provides longer life in tough conditions.
Pro Comp All Terrain
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Pro Comp All Terrain

Not just a smooth and quiet high performer on the road, this true all rounder also excels in dirt, rocks and snow. The sipes not only offer flex to the lugs but provide unbelievable traction in ice and snow winning the prestigious "Severe Weather" rating in USA.

The All Terrain is used widely among mining and forestry applications for its rugged reliability and terrific traction in such a wide range of applications. Also comes with a 80,000 km warranty.
Pirelli Scorpion A/T
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Pirelli Scorpion A/T

The Pirelli Scorpion A/T ranks high for versatility, all-terrain handling and sheer ride comfort.

Its tread design has been formulated to provide maximum traction in mud, snow and gravel, making the Scorpion A/T an excellent choice for gruelling off-road excursions. A robust construction offers high resistance to damage.

Even better, the Scorpion A/T provides exceptional on-road handling, with good driving comfort and low noise.
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Cooper AT

The latest 4WD tyre design philosophy is a closed shoulder block to reduce heel and toe wear, and an open centre tread design to self clean when off the road, unlike older designs with sharp, or open tread shoulders for digging. The new Cooper A/T gives good mud and sand traction without compromising wet grip on the road.

Cooper has a multi-layered steel cord belt and an extra rubber layer fitted between the belts to absorb more impact and reduce damage. Straight Sidewall design also deflects objects and reduces damage. Cooper designs the tyre to give high mileage without tie bars so they grip all through the tread life, making them safer. Tiny sipes or cuts in the tread also add to wet grip because they open as the tyre turns and virtually squeeze the water away.
BF Goodrich T/A KO
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BF Goodrich T/A KO

With BF Goodrich’s T/A KO, not much has been overlooked in the quest to meet the needs of SUV drivers who demand a lot from their tyres. The list of features is impressive.

Rim protectors moulded into the lower sidewall of the tyre shelter it from off-road hazards. The T/A KO’s computer-optimised tread design generates less noise. Twin steel belts provide strength and durability.

The T/A KO is a go-anywhere tyre that offers confidence and control for drivers of recreational vehicles.
Once you've selected the optimum tyre for your driving usage whether it be HT, AT or MT, you need to understand some basic rules for obtaining maximum longevity from your tyre investment plus you need to observe some safety issues regarding tyre pressures when travelling.

Most tyre manufacturers recommend that 4WD
tyres are rotated every 10,000km (check these specifics with your supplier as warranty conditions may be affected). Rotation is important in a 4WD vehicle because each tyre will wear differently due to breaking, cornering and weight distribution factors. If the vehicle operates in constant 4WD, all wheels are driving wheels, but if not, then whichever are the driving wheels (front or rear wheel drive) will also wear quicker. The more evenly your tyres wear, the longer life you should achieve. Obviously it goes without saying that tyre pressures should be regularly checked for the same reasons.

When travelling on dirt roads with a heavily loaded vehicle (usually adding weight above the standard vehicle's tyre-rated load capacity), a few important rules need to be observed:

To ease the comfort of the ride and to aid in traction on particularly bad corrugations, it is best to reduce tyre pressures about 4 -6 psi lower than what you run on the bitumen with this same load. Very stony country, such as the Birdsville Track, can handle even softer tyre pressures. This may not seem to make sense at first, but if you consider that your tyre is just like a balloon being bounced over sharp objects then you can see how the higher pressure would make it more prone to "popping" - termed by tyre manufacturers as stone fractures. This is most common reason for flat tyres occurring on outback roads and can be easily avoided by reducing tyre pressures.

It is also far preferable to keep speed constant and if possible around 85km/hr over corrugated roads (presuming the road is free from washouts and corners and it would otherwise be safe to do so). You will find that you can "ride" over the worst of the corrugations, provided your tyre pressures are reduced as suggested above. Any faster can be dangerous, slower and the corrugations may shake you and your vehicle to pieces. If handling of your vehicle appears poor, then a good look at suspension might be prudent. The best indication is "bottoming-out" when travelling as per the above suggested optimums. Most 4WD vehicles do not come with a suspension system that is rated to handle the load that is carried for extended trips (ie. water, fuel, supplies and spares). The correctly rated suspension-weight load ratio will also aid in improved tyre wear and longevity.

There is no perfect tyre or tyre pressure and a combination of speed and driver skill (plus a little bit of luck) will be the secret to minimising flat tyres and maximising tyre wear.

Tyre pressures are best checked when cool, because hot tyres give an incorrect reading. And don't forget that tyres on an off-road trailer can be inflated and deflated to suit conditions as you would your vehicle.

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