7 Degrees Celcius - Oh No !

Paulr said:
The tread on winter tyres is also designed to throw snow out of the depth of the tread - summer tyres tend to hang on to compact snow in the treads so they get even worse, particularly when they snow gets iced in the treads as well.
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This is a widely held belief that is completely incorrect. In fact the opposite is true...

Winter tyres are designed to hold onto snow, partly in deeper, wider grooves (which are better at displacing more water) but mostly within the small sipes across all the tread. Rubber on snow has very little grip but snow on snow grips pretty well. If you don't believe me try sticking a piece of rubber to snow and then try it with snow (it's how a snowball works).

Here is a picture to demonstrate the difference. The visible tread that is contacting the surface with a summer tyre is just rubber (having usually filled the grooves with snow) whereas the winter tyre has snow hanging off it all over.

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All season tyres are not much better in snow/ice than summer but notably poorer the other 90% of the time so in our climate are kind of pointless. I take the gamble of not being able to drive in snow and stay on summer tyres because they work alright on 364 days of the year. One day I may actually bother having two sets of wheels with winter tyres on one, but until I have a car with a big surplus in power over grip it's not really needed.

Interesting piece on winter vs all season: http://www.bmwblog.com/2014/11/26/season-vs-snow-tire-bmw-winter-test/ Note the winter tyre holding a lot more snow than the all season, which is not really any better than a summer for tread pattern, just the compound being a bit softer.
 
Didn't know that, I was always told the wider gaps in the grip was to throw the snow out - like mud tyres do. What you say makes sense though.

Never to old to learn, eh!
 
To be fair most journalistic articles are wrong and state that the tyres are designed to clear snow.

Winter tyres are better at dispersing larger volumes of water.

The reason they are worse when it's warmer is because the tread moves around too much and wears out faster. There is something called the glass transition temperature which is the point where the molecules of the rubber move notably more or less either side of that point. That point is lower for winter tyres so they remain more elastic when it's colder.

However, if you go too far the other way then the molecules move too much which causes the accelerated wear. Summer tyres with their higher transition temperature don't move enough when cold but consequently stand up better to 'heated use' when grip is good.
 
The highly respected Auto Bild have published their latest 'all season' tyre review,

http://www.tyrereviews.co.uk/Article/2017-Auto-Bild-All-Season-Tyre-Test.htm

Michelin CrossClimate (which I have on one of my cars) "As good as a summer tyre on dry roads, short wet braking distances, low rolling resistance"
Goodyear Vector 4 Seasons 2 "Almost as good as a winter tyre in the snow, very short wet braking distances, very quiet and comfortable"

Tyrereviews shoot out https://www.youtube.com/watch?v=zNuqGUgbcIk

http://www.tyrereviews.co.uk/Article/Is-there-a-true-all-season-tyre-We-find-out.htm

"All three non-summer tyres outperformed the summer tyre in both snow traction and braking by a huge margin"
 
Was out yesterday (Sunday) for a drive round the Dales

-3 when I set off

For the first 20 miles or so the Pirelli PZero’s felt like concrete and had absolutely zero grip

Once they had warned up they became more pliable and started to grip but I stil had to tread with care

My other car has Dunlop Wintersports on it ., the difference in them in the cold is night and day
 
Just a comment re tread wear on winter tires.
I had a set of Blizzaks ( a superb winter tire) on the back of my M3. Why, is a long story better told in a bar. Put them on in July, I drove the M3 all summer and through the winter and found the tire wear to be reasonable, probably the same as Michelin PS’s. I was surprised as I believed they would melt away on hot summer roads. They were so good in the winter that it is my tire of choice for winter here in Canada.
 
earthdweller said:
Was out yesterday (Sunday) for a drive round the Dales

-3 when I set off

For the first 20 miles or so the Pirelli PZero’s felt like concrete and had absolutely zero grip

Once they had warned up they became more pliable and started to grip but I stil had to tread with care

My other car has Dunlop Wintersports on it ., the difference in them in the cold is night and day
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Another out early Sunday. On the un-gritted minor roads of Dartmoor, there were some proper treacherous patches of ice. Not helped by the sun just poking it's head over the horizon and straight in my face. Had a few interesting moments. One in particular, at about 5 mph, were it was obvious the Zed was going to be sliding down a frozen section of road towards a bend. Just had to ease on to it, slide across to the dry tarmac on the other side and hope nothing came around the corner, up the hill during those few heart stopping seconds.

Then, after my walk, heading back in the evening twilight as the road was refreezing, the back was twitching on every other corner. I don't think I've ever driven like such a granny in my life before. I love a nice granite wall as much as the next man, but there are times I wish they were made of cheese. :D :driving: :thumbsup:
 
I have winter tyres on just in case.
Also means my summer wheels are nice and clean in the garage. Not too worried about the 103s used over winter with the salt.
 
Spent some time working in Russia, did a winter out there. Studded tyres not only mandatory but absolutely essential. But they are great, certain rules in Russia that you dont have to worry about there as here such as clean readable number plate and speed as the rental Audi far out paces a Russian cop car so boot down and charge on. Roadside check where they wave you down with the orange baton... Ignore em boot down they don't chase they just wait on an easier target. We did hundreds of miles ton up across solid ice and snow and the studs kept everything in line and fine.
 
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