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A Guide to Overland Tires

For Overlanding, we need our tires to perform flawlessly on and off the road. We need tires that have the ability to get us through mud and sand but we also want a smooth ride when we’re on the highway. The difficulty is finding tires that check all the boxes.

Tire manufacturers realize this, and so they offer three broad types of tires for our Overland vehicles:

  • Highway Terrain (H/T)
  • All-Terrain (A/T)
  • Mud Terrain (M/T)

In short, Highway Terrain tires feature all the qualities of regular passenger tires, such as variable tread block pitch and shallow tread with small voids. They are perfect for city driving, offering low noise, good ride comfort, and high-speed durability and handling.

All-Terrain tires usually feature more depth in the tread and bigger voids. They are more puncture resistant, often have greater load-carrying capacity and, of course, provide better off-road grip. They are also more expensive (as a rule).

Mud Terrain tires have even more depth to the tread with bigger voids, plus some tread that sticks out more for maximum traction in hard-core off-road situations. They aren’t so great on pavement, but they’re just the things for your more gnarly off-road encounters. They are usually relatively expensive.

Highway Terrain Tires

Of course, if all roads were sealed and it never rained, tires could simply be made of slick rubber; that is, without tread, which is used to expel water and avoid hydroplaning – a nasty predicament affording the driver little control. But as most drivers expect their vehicle to handle and perform well whatever the weather, road-biased tires feature very fine grooves to help expel water. Not exactly the perfect thing for a muddy trail, but the best option for pavement.

Along with shallower tread depth and lower noise levels, H/T tires often afford lower heat generation, and so improve high-speed durability. Thinner belt cord wire and a smaller number of belts give H/T tires great ride comfort because the tire casing is more pliable.

On the downside, with a thinner sidewall gauge, sidewall puncture resistance on H/T tires is usually lower than for A/T and M/T tires. Lower casing strength also limits maximum inflation pressure, reducing load-carrying capacity accordingly.

H/T tires are the sensible option for those Overland vehicles that spend most of their lives on sealed roads. That’s why many new 4WDs are fitted with road-biased tires, making the quick test drive around the block as smooth and quiet as possible.

So, before you change your H/T tires for something more robust, ask yourself this: are the tires on your Overland vehicle sufficient for your needs, or do they lack in one or more areas? Do you want a smooth ride and good road handling, or are you after an improvement in off-road performance?

If you’re never planning on going off-road, (we’re sorry to hear that) stick with H/Ts – you’ll enjoy good road performance and save money in the process. 

Do you think all tires are just regulation rolling rubber? Those boring bits of your truck that touch the ground? Well, you wouldn’t be alone, but the truth is it’s the simplicity of their function that make tires so important.

Basically, tires make contact with the road (or track, or trail, or rock) surface, grip onto it and thereby allow the mechanical components of the vehicle to transfer power and torque to the ground and move the vehicle.

In doing this, tires become intrinsically linked to all those factors of the vehicle that most interest owners, such as its handling, performance, fuel economy and safety. Imagine sticking a set of truck tires on a hatchback – you’d get an awful ride, terrible fuel economy and terrible handling, not to mention a smashed-up car when the thing went belly up.

All-Terrain Tires

If you’re like a lot of Overlanders, you’ll want the tires on your rig to take you to work, negotiate potholes and shopping center parking lots, handle highway speeds, then deal with dirt roads, muddy trails and rocky slopes – a big ask.

As the majority of 4WDs spend 80 percent of their life on paved surfaces, 4WD owners need to realistically assess how much off-road driving they do so that they can buy what they really need.

If you plan to be doing a fair amount of dirt-road touring, well-formed trail driving and a bit of sand or mud, then A/T tires are probably the best bet for you. And, in recent years, the technology used to create All-Terrain tires has advanced dramatically. A/T tires have never been quieter, safer or more versatile.

Generally speaking, A/T tires have a deeper tread depth than H/T tires, offering improved wear life and puncture resistance. They offer improved off-road performance, especially in soft conditions.

The usually stiffer casing than H/T tires can reduce ride comfort, but can help to increase casing strength and load-carrying ability. Often, A/T tires are of a heavier belt cord wire style, often with more belts than H/T tires. This can limit the speed-capability of the tire (due to greater heat generation) and increase noise levels, but this is less of a problem with latest-generation A/T tires.

A/T tires are the best bet if you cover a lot of different and relatively difficult terrain in your truck or SUV. They allow you to drive safely and securely on sealed roads to get the off-road destinations you bought your Overland vehicle to take you too.

Mud Terrain

If you do a lot of heavy off-road work, in addition to off-road recovery gear, M/T (Mud Terrain) tires may be for you. Are you one of those intrepid Overlanders who regularly take their vehicles into serious off-road territory? It is for this reason that Mud Terrain (M/T) tires exist.

H/T tires feature all the qualities of regular passenger tires, A/T tires are more robust and provide better off-road grip, but M/T tires are different animals entirely. Mud Terrains have much more depth to the tread with bigger voids, plus some tread that sticks out more for better traction in serious off-road situations.

Back in the old days, tractors were fitted with steel plates welded to the wheel, like paddles. In soft ground, these worked a treat. 4WD tires of a similar design are useful in some super hard-core off-road situations, but try using them anywhere else and you soon realize their limitations … we’re talking serious road noise, not to mention damaged driveways and some carved-up roads.

While some Mud Terrains do employ a paddle principle but with more versatile materials, most M/T tires are of the block-design type. These work like a spiked wheel, meaning only the actual tread component penetrates the surface, doing less damage to it.

The major downside of these tires is that they tend to pick up mud within the treads, and if this mud is not expelled before that portion of tread performs a revolution, the tire will act like a slick; this is obviously the last thing you need on slippery mud. To counteract this problem, many manufacturers have developed their M/T tires to be self-cleaning. This means the tires are designed to flex and, in the process, expel mud. These tires often self-clean more effectively at lower pressures.

A tire with aggressive mud tread has less grip on the road (and will wear faster) than more road-oriented tires, due to the lower amount of rubber in contact with the ground. So fitting M/T tires means compromising your 4WDs road manners for off-road agility. Other problems with M/T tires are they’re noisy and prone to heat build-up, plus they almost always increase fuel consumption.

While taller Mud Terrain tires are your best bet for serious off-road work – the increased tire height giving better ground clearance and approach, ramp-over and departure angles – the height change will increase the center of gravity of the vehicle, so it will exhibit more body roll and handling will suffer accordingly.

Rugged 4WD tires are essential for those working on the land or battling hard-core off-road conditions, but they are not the best choice for most Overlanders. Saying that, a beneficial addition to your Overland gear supplies would be a good set of Mud Terrains handy to swap over with your road tires on a full-on off-road foray is not a bad idea if you have the space to transport them – not to mention the spare cash to buy them.

Tire Terminology

Aspect Ratio

A numerical term which expresses the relationship between the standing height of the tire and the cross-section width. For example, an aspect ratio of 70 means the tire section stands approximately 70 percent as high as it is wide between the sidewall. Lower aspect ratios provide superior handling at the cost of increased ride harshness. Higher aspect ratios give a smoother ride.

Bead

The part of the tire shaped to fit the rim. Made of high-tensile steel wires wrapped in woven fabric and held by the plies.

Cord

The twisted fiber or filament of polyester rayon nylon or steel that gives the tire carcass and belts strength

Diagonal (Bias) Tires

These have two, four or more body plies, which cross at an angle to the centerline of the tread to strengthen both the sidewall and the tread.

Front Wheel Alignment (FWA)

Adjusting the angles of the front wheels so that they are perpendicular to the ground and parallel to each other. The purpose of these adjustments is to maximize tire life and have a vehicle that tracks straight and true when driving along a straight and level road.

Highway Terrain (H/T) Tires

Tires that have been developed for city work, offering low noise, good ride comfort, and high-speed durability and handling.

Inner Liner

The layer of rubber that is laminated to the inside of a tubeless tire to ensure the air-retention quality of the tire body.

Load Index

Relates to the maximum weight permitted for each tire at a set inflation pressure.

Mushroom Plug

An internal plug for repairing tires.

Nylon

Nylon is affected by temperature, climate and age but polyester is not. So, while other radials lose shape overuse, poly-bonded steel radials retain their dimensional stability throughout their life.

Over-inflation

Too much air pressure in the tire, which affects the tread contact on the road.

Ply

A layer of rubber-coated cords that run on an angle of 40 degrees across the tire carcass.

Radial ply

A tire with cords running radially from the bead at 90 degrees to the center of the tire.

Section width

The measured width of the tire at its widest part when inflated to the manufacturer’s recommendation.

Tread depth

This is the distance between the tire casing and the tread blocks.

Under inflation

A tire with a lower amount of tire pressures than specified, which affects the tread area on the road.

Valve

This is mounted either through the rim or as part of a tube and is how the tire is inflated.

Wheel size designation

This indicates the distance across the “hole” of a tire. You must match wheel diameter and tire diameter. For example, a 15-inch diameter tire must only be mounted on a 15-inch diameter rim.

X

As in 15×7, which is the wheel size, defined by the diameter and width of the wheel. A 15×7 wheel has a 15-inch diameter and a seven-inch width.

(Y) speed rating

The highest speed rating in a road tire. Rated above 186 mph.

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