Are Winter Tyres Worth it?

Monday 9th May, 2011
Regular readers will know that, towards the end of last year, I changed the Yokohama tyres supplied with my Lexus GS-450h for specialist Winter tyres. I wrote numerous reports along the way, here, here, here and here; but felt a final report would be of value to future readers.

Obviously, there is a significant up-front cost involved in choosing to use Winter tyres for the coldest parts of the year. Firstly, you need to buy new tyres - whether you need them or not - and then you need to pay to have them fitted to your wheels or even buy a spare set of alloys, as required.

The cost of the tyres themselves can be all but ignored, whilst they are on your car you aren't putting any wear on your summer tyres so you're saving an equivalent cost on those - assuming you spend about the same on winter/summer rubber. So, the only real cost is the time and money it takes to get the tyres fitted. Fitting is going to set you back around £100/set in a main dealer or around £50 in a specialist tyre fitters.

Winter tyres offer 3 main benefits. Firstly, they usually have 10mm of tread when new, compared to 6mm on a normal tyre. This makes them quite excellent in very wet conditions, massively reducing the risk of aqua-planing. I know first hand that this benefit alone is almost worth the money on very wet days when there are deep puddles at the side of the road. You hit a deep puddle and there is basically no deviation at all in the steering wheel - the car just carries on regardless.

Secondly, Winter tyres have special grooves (sipes) cut into the tyre which are designed to improve grip in powdered snow. In these conditions, the tyres are designed to actually trap snow in these grooves and use it to improve grip. Amazingly, snow actually has more grip on snow than rubber does. This can be demonstrated by rolling a tyre across powered snow. How much snow sticks to it? Not a lot. Now compare to a ball of snow rolled over snow - it gets bigger as snow is collected. That's, on a basic level, how these sipes work. Tread grooves in normal tyres are much wider and the snow basically falls out as the tyre spins - the narrow sypes are specifically designed to trap it.

Finally, Winter tyres offer major assistance in cold conditions and the soft compound is designed to be better than normal tyres whenever the temperature is below seven degrees Celcius. Having monitored the temperature whiilst driving over the winter, this was the case on an easy majority of the days. Also, when the weather is a little warmer, they're still extremely grippy - they just wear a little faster than a harder summer tyre might.

So, overall, would I recommend that drivers put the effort into buying winter tyres?

Absolutely! In fact, after just one season using them, I know I never plan to drive another winter on normal tyres.

In my case, I found the winter tyres to be considerably quieter on the roads (although the opposite to some other reports) and, due to the softer compound, I found the car was even a smoother ride across bumps and potholes. Obviously your experience may vary, depending on the properties of your existing tyre, but if you're just running a non-premium original equipment tyre you may well see an improvement across the board.

In the heavy snow, the grip levels were just amazing when compared to a normal tyre. They got me places that even light front-wheel drive cars didn't manage to go and, on the extreme snow day we had locally, they got me home in a normal time whereas colleagues took hours to get home as their normal tyres just proved useless. In fact they were that good in the snow that, when I chose to go out, I was choosing my winter rubber equipped Lexus over the 4WD we also had on the drive. The key difference was that, in the car with winter rubber, it actually stopped when I hit the brakes!

In the heavy rain, the ability to handle deep puddles at the side of the road was astounding. This is of particular benefit when the central reservation of the motorway had become waterlogged and you find yourself hitting deep standing water at rather high speeds. Not so much fun, however, for the guy behind, who is right up your back-end with normal tyres and has no appreciation for what is coming as you didn't really need to brake for the hazard.

Most important of all, though, is the grip in cold conditions. Whereas the hard compound of my Yokohama A10 tyres was pretty useless over the last winter, this winter the softer, cold weather tyres showed me a jaw-dropping difference. In a rear-wheel drive car, you know when it is winter. Launching away from traffic lights, you can easily try to put too much power down and feel the back end wiggle. The traction control kicks in, kills all the power and your fast get away is ruined. Likewise, on roundabouts or tight corners, you have to be careful with the loud pedal - squeeze it a little hard and the back end will try to come and say hello to the front as you enter a spin.

With the winter tyres in place, you can have much more confidence in the car's ability to stay on the road and also its stopping power when you need it. In fact, the grip from the winter tyres was so high, the car felt very different under hard braking. On the stock tyre, it stopped just fine and felt well balanced. On the winter tyre, the soft front tyres dug into the tarmac so hard when braking that I could actually feel the nose dip as the weight shifted forward. If I had the option, I'd have moved the brake bias to the rear slightly when these were fitted.

But what about black ice? It is highly regarded that nothing can save you in melting black ice - the surface of which basically offers no friction at all. If there is zero grip, can winter tyres really help? I thought not, based on the theory, but was proven wrong in practice and I believe it saved me a couple of times when the extra grip from the tyres caused my driving style to be over-zealous for the conditions. But how can they help? I'll explain.

Imagine my car, and its occupants, weigh 1600kg. Effectively, on level ground, that means there will be approximately 400kg of load on each tyre as the weight will be distributed equally. Now let's say, for argument's sake, that each tyre normally has enough grip to handle 600kg of weight. So, whilst the car has a weight of 1600kg, the tyres are capable of 2400kg - a nice margin for error.

Even if one of the wheels hits a pothole and momentarily skips off the road, you'll still have 3 tyres in contact which will handle a weight of 3 x 600kg = the car stays planted on the road. So far so good.

Now imagine that it's cold and those tyres aren't as good below seven degrees Celcius - as a result, each tyre loses a proportion of its maximum grip. We'll say, again just for example, that the maximum grip reduces from 600kg to 500kg. The total grip from four tyres is still 4 x 500 = 2000kg so still we have plenty enough grip for the 1600kg weight of the car, but what if one of those tyres then hits black ice? At that moment, you lose all the grip from one tyre and are left with the remaining three. 3 x 500kg gives you enough grip for 1500kg, which isn't enough and you end up sliding across the road until either a) you slide off the black ice onto tarmac and get your grip back or b) you have a nasty accident. Not ideal.

Now imagine you are fitted with winter tyres which handle the low temperatures just fine. Unlike the normal tyre, they offer 550kg of grip in the cold. So you have a total of 2200kg of grip - more than enough. Then, as before, one of those tyres hits black ice and you lose all of the grip from it. You're left with 3 x 550kg = 1650kg, so still enough grip to hold the car on the road and even a little bit to spare, allowing the Stability Control device to do its stuff and keep you going in the right direction.

In practice, this means you hit black ice on a corner wearing normal tyres and you go "WOOOAH!" as you slide uncontrollably across the road. When driving with winter boots on, you just notice the traction control light flash momentarily and realise you avoided something horrible. Winter tyres can't stop that 4th wheel spinning up on the melting ice but they can hold the other 3 in place whilst it happens. Much better.

So, in summary, I recommend that everybody consider winter tyres and, now the warm summer is upon is, this is the time to buy for the best pricing. If you wait until the Autumn, and demand increases, the prices will go up accordingly. Buy now, store them in your garage or shed over the summer and then get them fitted in September/October time. I can't really see any reason why you should regret it.

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