Winter Tyres - It’s not cold yet!

Wednesday 3rd November, 2010
This is one of numerous in-depth winter tyre articles I wrote over the winter of 2010/2011. Please click here for a summary of my results over the season and links to all the other articles.

I've now had the winter tyres fitted for a month and driven about 500 miles so I thought it was a good time to write up a quick updated.

Firstly, whilst it got very cold the week after fitting, the weather is still pretty mild. In fact, driving to work this morning, the outside temperature was about 16C - if you recall, the winter tyre benefits only really kick in at around 7C and below. So how well are they shaping up in the warm conditions? How well would they suit all year use? The answer is pretty well.

In my first report I wrote about how much softer the tyres were and how much extra grip they had. On closer examination, this was partly attributed to abnormally low tyre pressures - the fitter clearly doesn't understand how to read the tyre pressure sticker in the door jam on the driver's side of the car. In honesty, I can half understand - it is possibly the most complex bit of technical information you can fit on such a small area and the speeds only being in km/h can't have helped. Either way, my tyres ended up at least 10psi below the norm for any configuration. On inflation to a "normal" pressure, some of the old rough ride qualities returned but  overall things are still a lot softer and more balanced.

The tyre pressure thing has actually be a bit of a dilemma for me...what is a normal pressure? Lexus provide 6 different options for my tyre sizes, 3 for fully laden and 3 for a normal load of driver and passengers. The 3 pressure levels are based on speed - 100mph, 100-130mph, ~130mph = I'm guessing the latter means over 130mph. Opposite to uninformed logic, pressure levels are higher for the lower speeds - presumably at lower speeds the tyres don't get so hot so you rely on cold pressure to keep strength in the tyre walls instead. Too much pressure at a high speed, then the tyres will likely overheat and, at worst, wear out quicker. If you only drive at under 100mph then the tyre pressures are a no-brainer but you're also, possibly, driving the wrong car for your needs ;O)

For my needs, I inflated to the 100-130mph levels which still gives a comfortable ride and tightens up a little as the air in the tyres warms up at speed. You can clearly feel the softer compound rubber as you drive and, on a warm day like today, it can even be described as a little bouncy at lower speeds. The tyre doesn't skip off the road, like the Yoko's did, it stays planted - but there is an odd squidginess a bit like the feeling of walking on a grass field instead of pavement, or wearing trainers instead of leather soled shoes. The latter is a great comparison actually as, unlike the leather soles, these things grip fantastically. I notice it most under braking. At first I thought there was something wrong and then I realised it was just different to what I had become accustomed. When braking hard, the levels of grip are so high, the weight of the car is being thrown forwards over the front wheels. The nose of the car dips under heavy braking, like it never did before and, overall, it makes the car feel a bit heavier - but, if anything, it actually stops quicker.

The biggest difference, however, is in heavy rain. I've driven directional tyres with their distinctive chevrons in the tread pattern before but these are a whole new level. They say that a tyre with 1.6mm of tread will shift 2 litres of water per second at 60mph. Increase that tread to 3mm and that increases to 5ltrs/sec and a new tyre will shift up to 9 litres per second. This is for standard road tyres and these winter tyres were purpose built to shift standing water and slush. The end result is breathtaking and I've now driven home in heavy water a few times with no perceptible way of knowing it's raining - they simply drive like they do on a dry road. Even driving through a load of standing water, there is no deviation whatsoever.

So, in summary, I'm very impressed so far. On a hot, summer, day I may prefer a harder compound with stiffer tyre walls but I'd want these on every day that it was raining. The stock Yoko's are still looking like they aren't going back on the car.

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