As tyre specialists with an unrivalled wealth of expertise, you’d realistically expect our experienced team to know the subtleties and differences between the huge range of tyres on the market. And you’d be right. It’s why we can offer you expert, impartial tyre advice.
Conversely – and unsurprisingly – for the vast majority of UK drivers, the typical view is that all tyres are the same. When it comes to driver safety, nothing could be further from the truth. It’s a common misconception, since, at a glance, they can all appear the same as each other. But the reality is somewhat different, and vitally important to be aware of.
Why? Because if you deliberately or inadvertently mix tyres – particularly across the same axle – you could not only endanger your driver safety, but also end up on the wrong side of the law.
What are the differences between tyres I need to be aware of?
Basically, there are two distinct differences between tyre types. For the typical UK motorist, the most obvious one – because it can be seen if you look carefully – is the variation in tyre tread design. Different premium tyre manufacturers, such as highly regarded Continental, create their own different tyre tread patterns. Each tyre maker has its own view on how best water can be cleared from the road surface by the tread grooves. More on this later.
The other, more significant difference, is the tyre construction type. For car and van drivers, there are two main tyre build variations that they can typically fit to their vehicles. These are called radial-ply and cross-ply. Each build type has its own comparative strengths and weaknesses, since they deal with the stresses generated from driving in different ways.
And it’s because of these different characteristics – and the way that the tyres behave – that you should never mix and fit them together. Also, it’s worth remembering that just as different tyre makers create their own tread pattern designs, the same is true of the compounds their tyres are made from. These differ significantly from manufacturer to manufacturer, each having their own unique compound ‘recipe’.
Why you shouldn’t mix cross-ply and radial-ply tyres
The tyres fitted to your car or van are made up of many plies – layers – including rubber and cords of polyester, steel, or other textile materials – that, when fused together, give them the strength and resilience they need to support your vehicle, allowing you to drive safely.
Cross-ply tyres are diagonally overlapped along the length of the tyre crown (the top of the tyre), all the way down to the sidewall (the side of the tyre). This creates a solid, integrated unit, but means they are dependent on each other for structural integrity. It also means the tyre can warm up significantly under severe stress.
With radial-ply tyres, instead of forming an integrated crown and sidewall, the plies are arranged at 90 degrees to the direction of travel, or radially. In other words, the plies are layered along the centre of the tyre, across its length, and separate from the tyre sidewall. The two tyre elements are therefore independent of each other, offering more flex to the tyre. As a result, this reduces the build up of heat within the tyre.
Each of these two tyre types has its own benefits, depending on the vehicle they’re fitted to, and the stresses from speed and weight loads they’re anticipated to experience. And herein lies the reason you shouldn’t – mustn’t – mix them. If you do, you won’t attain a single, even stress tolerance across all your tyres, and this risks incurring tyre damage and having a blowout – increasing the chance of an accident.
For this reason, mixing cross-ply and radial-ply tyres across the same axle is illegal in the UK.
Advantages of radial-tyres include:
– Improved steering and contact with the road
– Better driving comfort due to flexible sidewalls
– Reduced heat generation at high speeds
– Higher resistance to tread-related damage
– Lower rolling resistance, leading to reduced fuel consumption
Advantages of cross-ply tyres include:
– Significantly improved vehicle stability
– Tougher, more resistant to sidewall damage
– Cost less to manufacture, and subsequently to buy
– Ideal for transporting heavy loads, such as for vans and light commercial vehicles
What about mixing different tyre tread patterns?
As with tyre construction types, mixing different tread patterns across the same axle is not permitted. The identical tyre model and tread pattern must be fitted for a single axle, though you can use different tyres on a separate axle – as long as they too also match each other.
However, tyre experts, including Asda Tyres, Continental, and TyreSafe – the leading UK tyre safety charity – strongly recommend that the same tyres are fitted on all wheel positions of your vehicle. Why? Simply because you will experience a consistent, even driving experience, without the risk of diminished performance that the mixing of tyres has the potential to lead to.
Don’t mix tread depths either
The same is true of fitting tyres with different tread depths across the same axle. Why? Because if one tyre has more tread depth than the other, it’s going to clear any water on the road surface at a different rate than a tyre with less tread depth. This imbalance has the potential to increase the risk of accident, since your car or van has to cope with different handling conditions that irregular water dispersion can cause. And it’s for this reason that tyre experts recommend that in the event you need to change a tyre – typically because of a puncture – that you do so for both tyres across the same axle.
Mixing tyre sizes is also a no-no
Just as with mixing different tyre manufacturers and tyre tread depths across the same axle, leading tyre experts like Continental recommend that you do not mix tyre sizes. Here’s why:
1. Mismatched tyres can throw off your speedometer, giving you a false reading and making you unaware of how fast you’re driving.
2. Having unequal tyres adversely affects steering, accelerating and general handling. There’s less grip and less control because steering feels sloppy.
3. Unequal tyres can mean it takes longer for your car to get up to speed – dangerous if you need a sudden burst to evade danger – and, perhaps more importantly, it also takes longer for you to come to a safe stop.
4. If one tyre is wider than the others, this will cause serious instability, particularly in wet or icy conditions.
5. Long-term, you’ll be at risk of damaging your vehicle’s wheel bearings, and even destroying the clutch.
The exception to the rule
Some cars – for instance, some rear-wheel-drive Mercedes-Benz and BMWs – come off the production line fitted with wider tyres on the rear wheels. This doesn’t equate to a mismatch, since the same tyres are fitted on any single axel, and the vehicle manufacturer has made a calculated decision to enhance the traction on the rear driving wheels. The OE – “Original Equipment” – tyres selected have been developed specifically for this purpose, by both the vehicle and tyre manufacturers.
If you’re still unsure about mixing tyres, talk to Asda Tyres
Talk to the Asda Tyres team of experienced professionals for impartial tyre safety advice, including about mixing tyres. We can also provide you with expert fitting solutions, and more. Click here to live chat to one of our experts, or find your nearest fitting station.