This isn’t a manhood-measuring contest. Bigger tyres don’t always translate to better performance.
Getting your first off-road vehicle is always an exciting affair. Not only do you now have a means of tackling the “great outdoors”, but you can also enjoy the fun of modifying it specifically for your intended needs.
There are tons of mods you can do to an off-road vehicle. Suspension lift kits, skid plates, bull bars, roof racks, and winches are just some of the many features you can add or adjust. However, arguably the most important mod you can do to an off-road vehicle is to fit it with chunkier, beefier off-road tyres. The kind that can tackle undulating terrain without returning flat as a pancake. A prime example is the Porsche 911 Dakar, which was given new life after the 911 was bestowed with hardy off-road treads.
But, as you think about incorporating such off-road tyres, do make an informed decision by learning how wheel size affects off-road performance.
If it isn’t obvious by now, larger wheels are heavier
I’m sure it’s common sense by now, every kilogram of added weight causes your vehicle’s performance to suffer. While it may not seem like too much additional weight when you opt for the larger 17-inch wheels instead of 15-inch ones, the wheel weight does add up.
As a minimum, you’ll need a wheel size that can comfortably clear the brake components on your axles, and these have been growing in size over time as well.
Larger wheels in most situations would also force your engine to work appreciably harder than their smaller counterparts. This additional weight is where the engine directly applies torque and this resistance, unsurprisingly, magnifies with more weight in order to rotate these bulkier wheels. This in turn affects your vehicle’s handling characteristics and rolling inertia, whilst robbing some precious engine power.
To remedy this, you can opt for wheels derived from lighter wheel materials. Steel, a common material found in off-roading wheels, is considerably heavier than some modern, lighter alternatives. While it can cost more upfront, wheels made from materials like aluminium can help give your off-road car more longevity in the long run.
For off-road performance, as a general rule of thumb, you should run a wheel diameter no bigger than half of the tyre’s overall height.
Wider Tyre Widths Offer Better Traction
Although big chunky tyres may affect off-road performance, they do significantly benefit traction when the going gets rough. Especially for those trails where the terrain can get treacherous, traction is worth prioritizing over performance in some circumstances.
Larger wheels have wider bases, which translates to a greater amount of surface area your car covers. This increases overall friction where you need it and helps you maintain control in any sketchy environments you might find yourself in.
Sidewalls are your friends
When you’re off-roading, the general rule is that the bigger the sidewall or higher the profile, the better you’ll be.
With a bigger sidewall, it provides more ground clearance underneath your vehicle while not compromising as much on weight due to larger wheel sizes (refer to above). Plus, in a pinch, you can always deflate the tyres to gain more traction, and larger sidewalls translate to larger contact patches when you air down.
How to choose the right tyre
Now there, don’t just head out and buy a set of shiny new BF Goodrich tyres. While expensive tyres are, in most cases, better, they might not actually be necessary for either your car or the trail you are attempting to conquer.
As a guide, here are three of the most common types of off-road tyres available on the market:
A/T tires are usually what you receive standard from the factory for most offroad vehicles. These tires are designed mostly for street driving, but also provide added traction over general street tyres should the need arise to participate in activities like trail riding.
Commercial Traction (C/T)
Although C/T tires are somewhat similar to A/T tires, they are designed with meatier treads and stiffer sidewalls. Their main advantage is they offer more off-road traction as opposed to on-road driving but are still suitable for day-to-day street use. If you can stand louder tyre road noise.
Maximum Traction (M/T)
M/T tires are the big bad wolves of the off-road world, designed mainly with off-road activities like mudding and rock crawling in mind. They have very pronounced wide treads, tougher beads, and tall yet flexible sidewalls that are perfect for airing down to increase your contact patch with the ground when you need more traction.
For more tyre guides, check out AUTA’s tyre guides here!