Michelin Tyre Takeaway

I was fortunate enough to be one of the winners of the Michelin winter tyre testing day at Silverstone, offered up on PetrolBlog last year. The idea being that Michelin were going to show me just how important winter tyres were, however learning anything about tyres was going to be a challenge with delightful Porsches to be distracted by. I’ll save writing about the cars ‘till later, and MajorGav has already gone into detail about Porsche’s experience centre here.

Winter Tyres

Winter tyres were the focus of this day, and the first activity after being briefed was driving a pair of 991 911s around the track, one on winter tyres and one on summer tyres. It was 8 degrees centigrade and a little damp on the day of the test, not prime conditions for the tyres, which are said to be at their best below 7 degrees. Perhaps the people at Michelin were hoping for it to be colder, but the imperfect conditions actually showed the tyres in a good light. A spirited drive around the handling circuit revealed no real difference between the tyres, which as far as I’m concerned is a good thing. The winters weren’t noticeably noisier, and the 911s were extremely grippy on both sets of tyres.

Michelin told us that in hotter conditions winter tyres require greater stopping distances than their summer counterparts, but that’s unlikely to be a problem you’ll have with British weather between November and March. Driving on public roads in a Cayenne S fitted with winter tyres was similarly normal. While we were offered no comparison in this instance, it was not glaringly obvious that car was rolling on winter rubber. No great difference then, but that’s hardly going to have the masses reaching for their wallets is it?

Fortunately Michelin allowed us to test the 911s on the kick plate at Porsche Silverstone, replicating the sort of low grip situations you could easily find on the road during winter. The Kick plate is a simple pneumatic plate that forces the vehicle to loose traction, just as your entering surface designed to be like sheet ice. My first go, in the 911 with summer tyres, resulted in a workout of the cars ABS system along with numerous rotations. I reacted like a man more used to correcting over-steer in videogames, too much lock. A second go with some enlightening words from the man from Porsche saw me able to return the car to traveling straight after it’s kick. Next up was the 911 shod with winter tyres. After the kick the Michelin Alpine Sports regained traction almost instantly, not requiring even a quarter of the effort from the driver that the summer tyres demanded. You might say that if you can still keep straight with summer tyres why bother? Well, I imagine there’s plenty of occasions when any driver will just be cruising along and not prepared for a sudden loss of traction, the winter tyres would afford you much better odds of not sliding your car into a ditch, or worse.

EU Tyre Labelling

You’re probably aware that new EU tyre labelling has come into effect, but before I didn’t really understand the process behind it. Michelin were keen to educate on the subject and I found their explanations quite interesting. After all this should be hugely helpful when buying a set of tyres.

First up is fuel efficiency; surely this will appeal to many, who wouldn’t like to save a bit on fuel? The difference in efficiency between bands A and G is around 7.5%, which on a car that averages around 50mpg could be as much as 4mpg, that could add up to many miles of extra driving over the lifespan of a tyre. The official test for this is simply the tyre being driven against a drum, which measures the rolling resistance of the tyre. The largest factor in reducing rolling resistance is reducing weight, so tyre manufacturers like Michelin are trying to find new ways to reduce the weight of their compounds. This also means that a worn set of tyres is more efficient than it was new, so there is at least one good aspect to a set of tyres wearing down.

Wet braking is measured using real cars in controlled environments. The time taken to slow from 50mph to 12mph on a controlled wet surface is measured, along with a test to show the friction between tyre and wet road surface at 40mph. These figures are calculated together to come up with the rating from A to F. In stopping distance the difference between these bands can be up to 18 meters, or 4 car lengths – not insignificant.

Noise is perhaps a less serious consideration, however it may be of interest to many. Like wet braking, noise is measured using real cars in controlled conditions. The cars must coast, with the engine off, at 50 mph on a set asphalt, the amount of noise is measured from 7.5 meters and this decibel figure appears on the tyres, along with a three bar symbol, less bars being better.

Takeaway

So did I immediately go out and buy winter tyres? Err, no, but I probably should have. Having laid out lots of cash (to me anyway) for my car last November, and then having Christmas I just couldn’t afford to invest. The manual for my car calls for 13” winter tyres, which will cost £241.04 for a set of four, and will require a set of £128 13” wheels to put them on. £369 isn’t an insignificant pile of cash. This year I fully intended to invest however. Firstly there’s more grip in these rubbish winter conditions, can’t argue with that. Secondly winter tyres are £16 cheaper than those I will have on in summer, meaning that over a couple of years of sharing the wear between two sets, the cost will be slightly cheaper if anything. Finally last year I had to replace a couple of alloys due to potholes, I imagine if I was running 13” wheels the greater tyre profile would do a better job of protecting the cheaper to replace steel wheels, win, win, win. The reason I say ‘fully intended’ is that now winter has come I find myself in the position where I must sell my beloved Puma, sad times.

As for the tyre labelling, it’s useful, but not useful enough. Which seems to be Michelins line too. Wet braking is important, but where is lateral grip or dry braking? Both seem like logical additions that have been neglected, Michelin claimed that these things were under review, but given the length of time it’s taken to get this far, it may be a while longer before we have the luxury of comprehensive tyre labelling.

Thanks again to Petrolblog and Michelin for this great experience!