What off-road 4WD tyres do you need?

Most new mainstream four-wheel drives are fitted with tyres designed for a basic level of roadholding, a smooth ride and quietness.

Despite ad campaigns showing 4x4s climbing mountains and crossing rivers, standard 4WD tyres are not designed to work in such off-road terrain for very long.

More often than not, you need to buy off-road tyres if you regularly travel in the bush.

In fact, tyres are the biggest single improvement you can make to your 4WD to improve its off-road ability.

Not only do good off-road tyres make the difference between getting grip or getting bogged when off-road, but also between getting tyre punctures or not.

This seemingly innocuous problem – a flat tyre – can quickly escalate, with two punctured tyres (a road tyre and the spare tyre) leaving many a 4WD stranded in the bush.

There are also many different types of off-road 4WD tyre, which can get confusing. Ideally, there would be simple classifications, such as on-road and off-road, but 4x4 tyre classifications are a little more complicated than that.

There are three broad classifications: Highway Terrain (H/T), All Terrain (A/T) and Mud Terrain (M/T).

Beyond that, there are two types of 4WD tyre construction: Passenger and Light Truck.

So let’s get down to earth and look at the different tyre types, what you’re legally allowed to fit to your 4x4, our basic tips on repairs, and more.

Highway Terrain 4WD tyres basically have a car tyre tread pattern to offer good on-road grip.

Of all the 4x4 tyres available, they’re also the lightest in construction, the quietest and the smoothest to drive on.

It makes sense that manufacturers fit H/T tyres as standard, as most buyers are city dwellers and sealed roads is where they drive most.

All Terrain tyres are more off-road oriented than H/T tyres. They often have a lower speed rating than an H/T, and with their stronger carcass construction they tend to have a higher load rating.

You can usually tell an A/T tyre by its deeper, more open tread pattern over an H/T tyre. However, A/T tyre design attributes are far more open to interpretation by the tyre manufacturer.

There is no international tyre rule that sets out what exactly an A/T has to have in its design and features. The result is some will have a tread pattern and construction close to that of an H/T tyre, others will appear chunkier and more aggressive.

In any case, a well-designed A/T tyre should have a stronger construction than an H/T tyre, which you work out by comparing the number of plies it has compared with an H/T tyre.

The A/T should have a chunkier, more pronounced, open tread pattern than the less aggressive H/T tyre tread pattern.

The A/T tyre is usually the best compromise for urban driving plus the occasional light Outback off-road or dirt road trip.

The better A/Ts for off-road work are those built with the stronger Light Truck construction (see below).

Mud Terrain tyres are the ultimate off-road tyre. They usually have a low speed rating and a high load rating, and typically the heaviest, strongest Light Truck carcass construction and a chunky, deep tread pattern.

Their tread pattern is designed for muddy off-road conditions, and while they offer good grip in other off-road situations such as rock shelves, they are not always the best for sand driving.

Also, M/T tyres can be very noisy and cause vibrations when driving on the highway and do not give the same level of grip on the tarmac as A/T or H/T tyres.

The M/T’s blocky tread pattern also usually increases rolling resistance and increases fuel consumption.

Despite their on-road shortcomings, M/T tyres are the go-to tyre for heavy-duty off-roading or remote country 4WD touring.

These tyres offer the best off-road grip overall, and with their heavy construction have the best puncture resistance.

There is another tyre type you will come across, called ‘Mud and Snow’ (M+S), which your 4WD might even have as standard.

These are meant to provide qualities that offer better grip in snow, ice or mud conditions but there is no M+S standard for grip or design qualities.

The M+S design is often not very different to a standard, passenger-rated Highway Terrain tyre. And don’t assume an M+S tyre design will work in the bush.

Passenger tyres (often designated with a ‘P’ before the tyre size, such as P235/65R17) are, as the name suggests, intended for passenger vehicles and not commercial load-carrying vehicles.

They will have a lighter construction, lower load rating but often a higher speed rating.

As you’d expect, Light Truck (LT) tyres are designed with a stronger carcass for light-duty load-carrying trucks so that they can meet the load requirements.

You’ll notice LT tyres have the ‘LT’ designation after the tyre size on the sidewall. Utes with a one-tonne or more payload usually have LT tyres as standard.

However, if you have a look at any new ute, you’ll quickly see that an LT tyre does not necessarily have an off-road tread pattern; they can look like H/T tyres with their on-road tyre tread pattern.

LT tyres can vary in toughness. The best way to check is by counting the sidewall plies on the tyre, and the more the better – usually at least four plies in the tread area and two in the sidewalls is a good indication of carcass strength.

Eight- or 10-ply ratings are better for resisting stone damage and sidewall staking.

In theory, a Light Truck-construction All-Terrain tyre is the best all-round tyre for a 4WD that will do urban duties well but also roll without dramas in the Outback.

Often these tyres will have a deep tread so they will take longer to wear out and not clog with mud as easily or suffer punctures as easily as an H/T tyre.

Buying off-road tyres is a bit more complicated than buying tyres for your family car. There are legalities that you can easily stray away from if you’re not careful.

Not only do you risk a defect notice and a fine, you might also end up with no insurance cover in the event of a crash.

A tyre placard sticker on your vehicle (usually found in a door aperture or glove box) will show recommended tyre pressures, the exact tyre sizes, minimum speed rating and minimum load rating.

But when buying off-road tyres, you’ll often find you’re very limited in tyre choices that meet all those requirements.

On a 4WD vehicle, you can legally fit tyres that have a minimum ‘N’ (140km/h) speed rating. You should then be good to go in most states and territories, providing taller tyres (or suspension) do not increase roof height more than 50mm over standard.

Be aware that taller tyres will change speed and odometer measurements; check accuracy with a GPS speed measurement. In some cases speedo modification is needed to keep the speedo accurate with taller tyres.

No matter what tyres you use, you must keep to your 4WD’s minimum load rating. You are almost always going to increase tyre load rating when you buy all-terrain or mud-terrain tyres, but check.

Not only is it illegal to run under-rated tyres, but with a laden 4x4 in particular, it could result in a blow-out.

If you choose wider rims and tyres, make sure that the tyres are still within the body of the vehicle – otherwise you’ll break the law. Tyres that extend out of the wheel-arches can scrape the guards and affect dynamics and/or be prone to blow-out.

There are work-arounds, such as fitting guard flares and trimming or rolling guards, but you’ll have to work out if this is worth the trouble and expense.

Even the best off-road tyre can be susceptible to punctures in the bush. You’ll need a tyre plug puncture repair kit, which should include at least 10 self-vulcanising plugs, a probe tool, insertion tool, razor blade and lube.

You’ll also need a 12-volt tyre compressor to reinflate the tyre.

Only the tread area should be plugged. If the sidewall is punctured or torn, don’t try to plug it unless it’s an emergency repair to just get you to civilisation.

Even then, drive very slowly until you can get the tyre replaced.

Off-road tyres – Quick reference: What you need to know
• There are three basic 4WD tyre types: Highway Terrain (H/T), All Terrain (A/T) and Mud Terrain (M/T)
• Standard H/T 4WD tyres are not well suited to Outback trips for grip and puncture resistance
• If you are planning regular bush trips, an A/T tyre in a Light Truck construction will give you the best off-road/on-road compromise
• M/T tyres are better for more hard-core off-roading but on road have less grip and are noisier
• Check legalities before buying off-road tyres, as they need to meet certain load rating, speed rating and size restrictions
• Carry a puncture repair kit and 12-volt air compressor to repair punctures when travelling in the bush