Your wheels and tyres are your vehicle’s feet on the dirt. The tread type, tyre and wheel size, and potential changes to track width all play a role in your vehicle’s ride, handling, comfort and traction.
The standard issue tyres are typically specified to optimise fuel economy and offer a smooth ride, plus good grip on mainly tar surfaces. When the same vehicle is used more often for overlanding and off-road purposes, those needs change.
There is a dizzying array of tyre choices to be made. As an off-roader, bear in mind you want stronger sidewalls and more grip. That means chunkier tread, and because you are also likely to go wider and perhaps taller than the standard issue tyres, this implies sacrifices in terms of more road noise and heavier unsprung weight. Too wide, and you will be looking at accelerated outer wheel bearing wear (because the wheel is hanging further outboard), plus greater loads on suspension components. Too tall, and your tyres might foul the wheel arches under full suspension compression and/or tight turns.
Most 4×4 vehicles these days come out standard with 18-inch tyres, typically sized at 265/60 R18, which is up from the specification of a few years back, when 17-inch tyres were the standard, usually 265/65 R17. Of course, serious off-roaders will argue these were already short on sidewall depth, having migrated from 15- and 16-inch rims, but the demands on braking as engine performance has increased, has also called for bigger diameter callipers – among other influences.
The point is, whether 18s or 17s, you are going to want to swap out the OEM tyres for something better suited to off-roading. What are the issues to consider?
The first question to ask yourself is, ‘What will be my majority use’. Don’t head straight to the gnarliest, biggest mud-terrain tyres out there if you don’t need them. On my Hilux Legend 45, my majority use is town driving. I want to dial in a comfortable, quiet ride. The tyre must grip in the dry and in the wet, and it must not too adversely affect fuel consumption.
Thing is, I also want these tyres to perform trouble-free on my overlanding trips, which are mostly confined to gravel, sand and mild rocky stretches of track. So I want a strong yet flexible tyre carcass that will also offer good flotation when deflated for sand.
Having just destroyed a set of rims and terminally damaged a few sidewalls on a set of chunky mud terrain tyres on Baboon’s Pass in Lesotho, I have sworn off crazy rocky trails for now. If I wanted to do more of these sorts of trails, my tyre criteria would differ.
With my typical needs in mind, I have fitted a set of Mickey Thompson Deegan 38 All Terrain tyres, in 265/75 R16 size. These tyres have been distributed since 2018 locally by TyreLife Solutions, who also handle local distribution of Cooper Tires. They come with the stamp of approval of serious off-road racer Brian Deegan, so I am assured the tread tech, rubber compounds and the carcass construction (which is rated Light Truck) will be from the top drawer.
Incidentally, Mickey Thompson, the guy who started building these tyres in the US, was a salt flats speed racer (first to reach 406.6mph on land) and off-road competitor, and claims to be the first to introduce “sidebiter” treads which run down the sidewall to make them tougher.
The Deegan 38 all-terrains are said to offer good mileage, traction at high speed in the wet because of the silica compounds used, and a strong puncture-resistant sidewall. I like the fact they are rated 116T, which means they have a good load index (1250kg per tyre) and a speed rating up to 190km/h – in excess of the ability of my Hilux. I am also hoping the taller 75 profile will not only add to my ground clearance, but also offer a more compliant ride.
It’s worth knowing that Mickey Thompson tyres carry a 10-year manufacturer warranty, plus (on registration) a TyreLife Solutions two-year protection plan and mileage warranty. These guys are trading on their longevity.
Next up, I needed a matching set of wheels. My 2015 Hilux Legend 45 came standard with 17×7.0/6×139.7/00 OEM wheels.
This means a 17-inch diameter wheel, with a width of 7 inches and PCD (Pitch Circle Diameter) of 139.7mm with six holes for wheel nuts. The double zero indicates the offset.
I wanted a more aggressive look, so was searching for a slightly wider rim, but one still within the fitment parameters of the wheel arches and suspension. For me that was a 9-inch wide wheel, but I was informed this would result in wheel rub, so took the safer 8-inch option.
Because of my tyre size I had to go for a 16-inch rim. Bear in mind this was compatible with my Hilux but might be too small for many of the larger brake calliper configurations.
In the Mickey Thompson range, now available in South Africa, I was drawn to the Sidebiter Lock Black, in the following spec: 16×8.0|6×139.7|00. The offset and PCD are a match for the Hilux, so no trouble there, plus they are rated at 1134kg each. This is one of the advantages of the Mickey Thompson range; the thicker rims offer the extra load carrying capacity and strength required by a 4×4 doing heavy-duty work, and taking knocks off-road.
You can get this rim in a smoother outer style, but I fancied the “bead lock” look with all those machined-out bolt heads. The satin-black finish is also pretty neat, and there’s a lifetime warranty against structural defects, which does add peace of mind.
All Terrain tyres and especially Mud Terrain tyres are difficult to fit and not always easy to balance. Choose your tyre outlet with care.
Twice now I have had a fitment centre damage a new wheel due to inexperience and even lost a brand new tyre.
Having the correct equipment to balance these heavier Light Truck tyres is essential if vibrations and plenty of return visits are to be avoided. My choice was Point S Multi-Tyre in Boksburg, who have a specialised “Road Force” balancing machine.
Tyres are not completely round, and slight material variations mean they might perform slightly differently under load. The Road Force balancer first uses a standard spin balance, then applies up to 650kg of pressure from a roller to simulate vehicle weight, enabling the optimum wheel/tyre position to be found. It takes a little longer, and costs more, but does iron out balance issues more effectively.
Wheel offset describes the location of the wheel mounting surface within the width of the wheel.
A wheel with zero offset has a mounting surface dead centre within the wheel width.
Positive offset means the wheel mount flange lies closer to the outboard rim of the wheel – the wheel tucks further into the arch.
Negative offset has the wheel mount flange closer inboard on the rim, causing the wheel to stick further out.
If you go for aftermarket wheels, you might need less negative offset compared to stock to keep the fatter tyres from hitting the fenders. If you’re installing an aftermarket lift, most companies can advise on what wheel size and spacing will work well for the application.