Recap: your tyres in winter

[rezulteo]

In a few months time it will be the end of winter, and before everyone sets off on their February holidays we once again offer you the chance to take stock of all the options available to you in terms of winter and snow tyres.

Winter tyres: the basics

We can’t say it enough but winter tyres are not just there for when it snows, they come into their own as soon as temperatures drop below 7°C. And if it does snow, you will be able to drive away safely as opposed to leaving your car stranded in a car park. Winter tyres VS Summer tyres: the performance differences speak for themselves…
Read more about the differences between a winter tyre and a summer tyre.

It’s good to know that on a speed indicator, European legislation allows the speedometer to drop to ‘Q’ when it comes to winter tyres (See the annexe text II 4.2.2)

However, in temperate regions where winters are more mild, all-season tyres and M+S tyres can serve as an alternative option. But be assured that this is not always a good compromise. Read about what an all season tyre worth in winter on rezulteo.

Nordic tyres: tyres for extreme winters

Nordic tyres are very rarely used in the UK as they are designed for use once the temperatures reach -10°C. They are thus mainly used in Scandinavian countries, where the roads are snowy for months on end and conditions are often icy. They are characterised by strong siping and a directional profile.

Studded tyres: guaranteed grip

Studded tyres are a type of Nordic tyre, but thanks to their studding they allow a better grip on snowy and icy roads. It is important to pay attention to regulations regarding their usage in a particular country. Think to check legislation concerning usage for particular regions and countries. It is also important to place a special adhesive sticker to your car and limit your speed to the equivalent of 90km (around 57mph). Read all about studded tyres on rezulteo.

Snow chains: When tyres are not enough

In the case of heavy snow this is potentially essential equipment; whether you put them on for skiing or are travelling in a snowy mountainous area. There are several types of snow chains available for different prices. It is very important to ensure you buy obtain chains with the correct dimensions, to maintain them and also to practice putting them on because fitting them for the first time in the snow can be very difficult!

It is good to know that snow socks also exist, and often at a lower price. Be aware of the fact that certain tyres are matched with a brand. Such as EasyGrip socks from Michelin. They serve as a quick solution to help you in tricky conditions but inform yourself about their use and performance when you buy them.

Pay attention to different regulations

Depending on the country, regulations concerning studded tyres and snow tyres can vary. Make sure that you are up to date by looking at our detailed lists of information for each country. Regulations for the use of winter tyres, snow chains and studded tyres in Europe.

And there you have it, some last advice for this winter season. Safe driving everyone!

 

[PAULF]

Rezulteo,

One thing about winter tyres that has always puzzled me is the temperature claims.
Generally it is accepted that winter tyres are better than summer at OATs below 5C as the rubber is a different compound.
However, it does not take very much driving to warm the tyres to above this temperature - so at this point surely they would behave the same?(I am, of course ignoring the differences in sipe and tread patterns)
I know the argument may be that the road is still cold, but it is the flexibility and stickiness of the rubber that is the changing parameter and this is dependant on the rubber temperature not the road temperature.

I use 195/65/15 Wintersport 4Ds on my B5 Quattros in winter, and 205/55/16 Michelin Pilots on the Avant and Yokohama C-Drives (?) on my saloon in summer. The difference on ice is astounding, and in snow - the performance is fantastic! (Mrs PaulF went through snow up to the bonnet rings last year)

I use the narrower tyres in winter, because grip is increased for the same rolling diameter (this was a size used by Audi so I have no compatibility issues). This is primarily due to the reduction in the co-efficient of friction between the tyre and road. (I won't go any further, as it gets silly complex )

 

[BahnStormer77]

"Thinner tyres in winter" is very old thinking. Its from the days when you needed the weight of the car to cut your wheels into the snow. It might get you better fuel economy, but it will NOT get you better grip: modern rubber just grips onto the ice or snow, so the larger coefficient of fraction (grip) comes from a larger contact patch.

And I'm happy to explain all the "complicated maths" if you want

And to answer the other question about tyre temps, unless you're on a track, you will NOT keep enough heat in the tyres and even if you are on a track, the first blip of dampness and you'll lose that anyway.

 

[PAULF]

"Thinner tyres in winter" is very old thinking. Its from the days when you needed the weight of the car to cut your wheels into the snow. It might get you better fuel economy, but it will NOT get you better grip: modern rubber just grips onto the ice or snow, so the larger coefficient of fraction (grip) comes from a larger contact patch.

And I'm happy to explain all the "complicated maths" if you want

And to answer the other question about tyre temps, unless you're on a track, you will NOT keep enough heat in the tyres and even if you are on a track, the first blip of dampness and you'll lose that anyway.

I was trying to keep it simple as it appears the jury is still arguing, but here goes anyway.........

I presume you are on about this type of equation - or do you have a better model with a higher order?



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There are some good explanations here Pelican Technical Article: Physics of Racing Series - Pelican Parts

However, as to the narrow/wide argument, a look here Fact or Fiction? Tire contact patch and air pressure. gives some good measured data as to the actual contact area, as opposed to the calculated one.
The problem with any calculation is the quality of the model, and tyre grip has many very clever people employed trying to work it out still - and flogging us their resulting product!
You could infer that the narrow tyre has a higher contact pressure, thus negating the lower coefficient of friction and at some point, providing a better grip.

The tyre uses either a long narrow footprint or a short fat footprint, depending on the tyre width. This effects the slip characteristic of the tyre when traveling in anything other than a straight line (imagine a fixed diff axle turning - a wider axle has a higher slip rate) with a fat footprint having better grip, generally but higher slip rate. If the grip level has been reduced by a very low coefficient of friction, the increased slip comes into play, reducing overall grip.

Bearing in mind as well that heat within the tyre is constantly generated by contact friction and sidewall flexing at a greater rate than is generally cooled by airflow - thats why you must wait before checking tyre pressures.

I would expect contact cooling to be almost nil whilst running, although the wider wheel does dissipate heat better and generates less due to less less sidewall flexing. This would mean for winter they run at a lower temp than the narrow tyre, implying a less sticky tyre.
Of course, driving icy country roads for an hour will generate much more heat than a 5 minute trip to the shop - another variable to try and take into account!

Of course, all of this does not take into account the tread/sipe patterns of the winter tyre, which have a great impact on winter driving ( which is, I think what Rezulteo is really pointing out). :icon_thumright:

 

[BahnStormer77]

Its the rubber compound that makes a huge difference too: even from the start in extreme cold, a winter tyre will be flexible and soft: my Wintracs were softer and more compliant at minus ten that my Toyo Proxes were at plus ten!

And the tyre wear of brittle summer tyres below 7c (40% faster) always as good one to throw into the debate

I'll check your numbers when I'm back on my PC.

Don't use race figures for road calcs though: they'll also recommend things like 30-40% slip rate for optimal snow acceleration, but I'd scarcely see my quattro's tc light on at all during snow driving... unless it got spirited, but then that's normally "TC off" time not great for tyres, especially if they're summer ones!

 

[PAULF]

Its the rubber compound that makes a huge difference too: even from the start in extreme cold, a winter tyre will be flexible and soft: my Wintracs were softer and more compliant at minus ten that my Toyo Proxes were at plus ten!

And the tyre wear of brittle summer tyres below 7c (40% faster) always as good one to throw into the debate

Agreed, I was musing on my way to work and that may be the answer.

Winter tyres are softer, giving better rubber adhesion to the surface at all temperatures, summer and winter. Winter tyre wear in the summer is very fast (as I found out when I drove for a couple of weeks with the rear tracking out!)
I think issue is not the compound, but the tread pattern. The winter tread pattern give better adhesion to the icy surface, but less so when the surface is not so slippery. Then the sipe and tread pattern/flexing will work against adhesion.
A little like slicks in the dry and channeled in the wet each tyre pattern works best in its own environment.

(only girls use traction control )

 

[BahnStormer77]

Depending on the brand/compound, most winter tyres will start to suffer around 20c and wear very fast over 25c. There's some people in Scotland running them year-round, but even they will see unreasonable tyre wear in the warmer (less cold) months. Not as bad as the excess tyre wear that you get running summer tyres through an English winter though!

 

[BahnStormer77]

Softer tyres and better flex also means the tyre doesn't get ice stuck to it in the same way that rigid summer tyres do....

 

[Ultra Violent]

Well that was definitley one of the more highbrow discussions on the winter tyre question. Koudos on the research.
I can only put my own personal experience across. Living In Scotland I do find the winter tyres make a difference.
during the winter I run on Goodyear Ultragrip 8's and I feel they really help, giving more confidence in harsh weather, especially snow.
During the summer (Apr-Oct) I use Eagle F1's, its hard to say if the weather has adverse effects on tyre wear because I switch them round. I know winter's aren't for everyone and a lot of people still claim its all down to the drivers but this is JMHO.

Scott.

 

[adamss24]

I often keep a cheap b5 quattro for use in winter as i find the dynamics of the chassis far exceed the b6/c5 platforms ! This year's i used a 1.8TQS avant fitted with 15" Nokian Haka tyres, no problem with grip whatsoever and i have a trick up my sleeve- i always remove the ABS fuse in winter as i can predict the way chassis behaves ! My other allroad on cheapo winter tyres have no problems in deep snow and such but the TC is interfeering every time- not a bad thing for day to day drivers but, after driving during hard winters in eastern Europe, i find it a bit too much !

 

[BahnStormer77]

Personally I just prefer holding down the esp button for a while to disable it.

 

[adamss24]

And how do you do that ? The ABS system just disregards the button if you keep it for too long, unless you're on the new models which have different systems ! Still ABS is pants on snow, studded tyres are the way forward !

 

[BahnStormer77]

doesn't disable ABS, just disables TC&ESP, so you can get controlled power oversteer and nice long drifts in the snow.

Just personal preference really: I don't mind ABS with decent winter tyres... but I don't really like the ESP snapping it straight all the time.

 

[Cabbyfan]

I had 4 new Michelin Primacy 3s fitted to my non Quattro cab. We had a good 2 to 3 inches of snow recently and on a trip there were several slopes where cars in front gave up and turned round and my cab did a great job. I did turn the traction control off at a fee points. I did feel a bit of a Pratt mind as almost every other vehicle I saw was a 4x4 and I was in a convertible ....I think if I didn't have new decent tyres on though I would have been stuck.

 

[BahnStormer77]

Like the Scandinavians say how you should have the right tyres first, 4wd second.

 

[PAULF]

What would be interesting would be how the rubber compound for winter tyres perform on a summer tread pattern.
I would expect great grip, but a very short life if my earlier musings were correct.

I managed to destroy one of my 15" alloys last week, so had to refit my 16" Yokohama clad wheels on my saloon. Yesterday going down my drive I spent a good proportion sideways. The Avant didn't blink.

I've been driving in Aberdeenshire for over 20 years now, and my experience is that as the tyre size increased in width, the traction decreased. (remember 2CVs in the snow, or my MkV Cortina with 165/80/13s!) Also the performance of a good set of winter tyres are unbelievable if you have never used them before.
I have slightly different issues to most as my drive fills in feet deep regularly, so I am often trying to get through deep snow. This needs a different tyre compared to driving on icy surfaces.
My L200 has 'oxo' clad tyres that are M+S, which is different to a winter tyre. This allows maximum grip by using the blocks to bite into the snow. Once on a (semi) cleared road they are rubbish - or if you have been stuck and spun the wheels too much and made a polished ice depression.
One of the worst feelings is after the snow has cleared, but in my drive there is about 6" to 1' of slushy compacted snow. The Wintersport 4Ds coped with this fantastically last year and cut my walking up and down period by at least half!

 

[PAULF]

I would also second Adamss24 thoughts on ABS.

A few years ago we had a 525i Auto (Ha, that was fun in the snow!!) and we got to the top of a down ramp at a car-park. There was a 6 month old small car (Corsa??) that had slid and hit the wall at the bottom.

Mrs PaulF tried to stop from about 5mph at the top of the ramp, but the ABS was having none of it so the BMW very slowly rolled down the ramp and destroyed the Corsa,(the BMW bent the steel bumper insert) ABS clicking away merrily.