SKINNY TYRES vs WIDE TYRES OFF-ROAD
While a number of 4x4 enthusiasts favour a bigger, wider tyre on their vehicle, many commercial 4x4 users swear by the benefits of a skinnier tyre. Game-farm vehicles are an obvious example. However, an increasing number of 4x4 owners are warming up to the idea of fitting “pizza cutters”, instead of their vehicle’s standard tyre size.
To be clear, we’re not talking about oversized tyres versus factory tyres (we’ve covered that topic here), what we’re comparing here are the benefits (and disadvantages) of fitting a narrower tyre, as opposed to the factory-specced units.
We’re essentially comparing two common sizes:
265/65/17 versus a 245/70/17, or a…
265/75/16 versus a 235/85/16
Both tyre combinations are approximately the same diameter; the difference lies in the tyre’s profile height in relation to its overall width. That said, what we’re asking is: Does a narrower, taller tyre have any off-road benefits when compared to a wider, lower-profile tyre?
Let’s take a closer look…
The benefits of a narrower tyre are well known in muddy conditions, where a thinner tyre is more likely to cut through surface mud and find firmer ground below. However, this is only true to a certain extent, and applies to relatively shallow mud depths. Fortunately, most muddy roads are only surface deep, so there are definite advantages to fitting a narrower mud-terrain in areas of high rainfall.
The benefits of a wider tyre seem obvious on rocky terrain, where you would expect that a greater weight distribution and width would help with puncture resistance and traction. However, contrary to popular belief, because a wider tyre spreads its mass over a greater area, it also impedes the tyre’s ability to conform to the terrain (i.e. increased deformation depth), particularly in the case of an aired-down tyre. In other words, narrower tyres are more likely to “wrap” themselves over rocks, increase traction, and reduce the chance of slippage.
Needless to say, a vastly oversized tyre offers many more benefits in terms of rocky terrain (traction, puncture resistance and ground clearance) but for the purposes of this article, we’re comparing factory-sized tyres at a predetermined diameter.
Because sand is so varied in texture, depth and cohesion, it’s too diverse to draw any conclusive arguments. In some cases, a wider tyre will prove beneficial in sand, but in other scenarios, two primary requirements remain unchanged: The need for momentum, and the ability to air down.
Thanks to their taller profile, thinner tyres tend to “stretch out” more when deflated, offering a longer footprint and greater off-road traction. What’s more, thinner tyres are generally lighter, have a lower rotational resistance, and may offer some benefits in terms of engine power, friction and momentum.
Coming back to the subject of game-farm vehicles: One of the greatest threats to a tyre in bush veld conditions is the risk of sidewall damage. This usually happens as a result of a broken tree stump, root, or half-embedded rock. What’s more, typical driving habits are slow and cautious over unknown terrain.
For these reasons, a thinner tyre is often preferred for its lighter steering response at slow speeds, less strain on the drivetrain, better fuel economy, and the fact that a narrow tyre is easier to accurately steer around potential obstacles and sidewall hazards.
Like most tyre discussions, there’s no clear winner in the fat-versus-thin debate. Where a narrow tyre excels in one application, a wider tyre performs better in another. You only need to drive on a wet-tarred road to know how beneficial a wide tyre can be.
In saying that, the off-road performance of a tyre isn’t the be-all-and-end-all of 4x4 ownership; daily driving habits, safety and functionality are also undeniable considerations. Which is why so many workhorse 4x4s come factory fitted with “Marie Biscuit” tyres, while the average double-cab is clad with the wider alternative.
However, no matter what your preference, the subject of thick or thin doesn’t count for much if your 4x4 is running on P-Metrics and not Light Truck tyres. So start your tyre search with the largest selection of Light Truck tyres on the market by using our Tyre Finder here.