Use of 'summer' tyres below 7 degrees

[clk270]

Well i logged in again this year to see whether Bill had changed his views, nice to things haven't changed !

The often quoted temperature of 7'C is the average daytime temperature - bear in mind most people commuting at 6-8am and again at 5-8pm are driving at temperatures lower than the daily average.

And yes, not to dissapoint, one on my cars is now on its winter tyres and the daily user will be within the next 2 weeks. I'm happy to wear my £55 winter tyres out for 4 months while the £120 ones sit in the garage.

And folks don't lose sight of the fact that a summer 245/40/17 tyre for an SLK has rather different design criteria to a 195/65 for a W124 (one being specifically sports orientated and the other comfort, mileage, all round performance). As such tyre structure and compoumnd are completely different. Tyre width helps tremendously in snow (hence why Beetles / Minis never had an issue) but compound and tread design are just as important.

Nice bit of snow on the East coast of the USA - will be in UK in ~ 10 days ?

 

[markjay]

...The often quoted temperature of 7'C is the average daytime temperature...

The figure of 7 degrees is generic - apparently different manufacturers have different figures - Continental recently quoted 2 degrees as the temperature below which their winter tyres out-perform their summer tyres on dry or wet roads (i.e. not on ice or snow).

 

[rf065]

Regardless of the science, economics or otherwise of summer or winter tyres, the thing that made the most difference to me is the width of the tyre. My w202 c230k R17 245/40 tyres are worse than useless in the snow and ice. My w124 tyres (R15 195/65) are much much narrower and cope with snow the w202 couldn't hope to negotiate.

That is only the science of summer tyres,
A 245/40 winter tyre would perform in the snow without any problem at all.

There was a good test of a Jag going round a race track on you tube with 275 section winter tyres in the snow, they did not hinder it one bit despite their width.

Russ

 

[BTB 500]

The figure of 7 degrees is generic - apparently different manufacturers have different figures - Continental recently quoted 2 degrees as the temperature below which their winter tyres out-perform their summer tyres on dry or wet roads (i.e. not on ice or snow).

Of course in the What Car? dry road / 5.5C test none of the winter tyres outperformed the summer one from the same maker (they were nowhere near - the Conti winter tyre took almost 18% further to stop than the summer one). So I would still personally be sceptical about the oft-quoted 7C.

 

[BTB 500]

Well i logged in again this year to see whether Bill had changed his views, nice to things haven't changed !

The difference is that previously I only had my own experience of driving on 'normal' tyres in cold weather to go by. I've never noticed any loss of grip on dry but cold roads (even below freezing), so I had a really hard time believing the claims about winter tyres being better on all surfaces below 7C. Now there are some hard test results showing both premium and budget winter tyres being seriously out-performed by their summer counterparts at 5.5C.

That's all this thread is about - nobody is disputing that winter tyres are better on snow.

 

[rf065]

Now there are some hard test results showing both premium and budget winter tyres being seriously out-performed by their summer counterparts at 5.5C.

They may have been a slight performance advantage in favour of the summer tyres at 5.5C, but not seriously out performed.

The serious out performed would be when it does get colder and then the summer tyres are not even in the same ball park.

Russ

 

[Dieselman]

They may have been a slight performance advantage in favour of the summer tyres at 5.5C, but not seriously out performed.

The serious out performed would be when it does get colder and then the summer tyres are not even in the same ball park.

Russ

Do you have any test results to show that the cold affects the summer tyre performance or is it just that Winter tyres perform better on snow due to the open tread blocks?

 

[markjay]

The difference is that previously I only had my own experience of driving on 'normal' tyres in cold weather to go by. I've never noticed any loss of grip on dry but cold roads (even below freezing), so I had a really hard time believing the claims about winter tyres being better on all surfaces below 7C. Now there are some hard test results showing both premium and budget winter tyres being seriously out-performed by their summer counterparts at 5.5C.

That's all this thread is about - nobody is disputing that winter tyres are better on snow.

I generally support your views on this issue, and while I agree that any performance deterioration in summer tyres performance due to temperature drop - on dry and wet roads - is negligible, I also acknowledge that on snow and icy roads winter tyres win hands down.

I think that the temperature-related performance issue is purely academic, and has very little affect on real-life driving in the cold. I imagine that a top-brand premium summer tyre will still out-perform a cheap budget non-branded winter tyre even at 0 degrees - on a dry or wet road.

So I think that ultimately the decision regarding use of winter tyres is really down to how many snowy / ice days there are in your area.

For me personally - I don't drive much, and my trips are not essential so I can afford to stay at home when the weather is bad.

Looking back my last 15 years of driving - in 1998 I was unable to turn into a residential road due to black Ice driving a (RWD) Scorpio. Then for 11 years I never drove on ice or snow. In 2009 I was unable to drive uphill in Kilburn due to ice, so had to give up. In 2010 I drove 3 miles in very heavy snow at an average speed of 10 mph. So for me personally - living in London and given my other circumstances - driving 6 months a year on Winter tyres to avoid a one-off snowy or icy day is simply not the right decision.

I do accpet, however, that if you are unable to get the car on or off the drive when it snows, or you live in an area that sees much snow and ice during winter, then winter tyres are a must.

 

[BTB 500]

They may have been a slight performance advantage in favour of the summer tyres at 5.5C, but not seriously out performed.

It depends how you define 'serious', of course. The stopping distance from 62 mph for each winter tyre compared to the summer one of the same brand was as follows:

Continental: +21 feet (18%)
Goodyear: +20 feet (16%)
Michelin: +18 feet (15%)
Nankang: +17 feet (13%)

Those differences seemed significant to me, when winter tyres were supposed to perform better.

 

[rf065]

Do you have any test results to show that the cold affects the summer tyre performance or is it just that Winter tyres perform better on snow due to the open tread blocks?

I can only draw on a lifetimes expererience of using summer tyres through the winter. After 5 years of using winter tyres, I would not even think about running summers through winter ever again.

Russ

 

[rf065]

It depends how you define 'serious', of course. The stopping distance from 62 mph for each winter tyre compared to the summer one of the same brand was as follows:

Continental: +21 feet (18%)
Goodyear: +20 feet (16%)
Michelin: +18 feet (15%)
Nankang: +17 feet (13%)

Those differences seemed significant to me, when winter tyres were supposed to perform better.

I define serious when tests show the winter tyred car completing the test without drama while the summer tyred car could not get past the first incline and failed to go any further.

Or the two Jags on the race circuit, summer tyred car needed a push to get off the line but did complete the lap. Winter tyred car needed no assistance and completed the lap 30 seconds quicker. This was not even on snow but a mixture of wet track & slush.

I can live with the stopping distance being slightly longer in milder weather, simply leave a bigger gap & drive accordingly. What I cannot live with is sliding around and going nowhere when the weather gets nasty.

Russ

 

[BTB 500]

I define serious when tests show the winter tyred car completing the test without drama while the summer tyred car could not get past the first incline and failed to go any further.

You see I would regard not being able to stop as being more serious than not being able to start off - all down to personal priorities I guess! I've actually said many times that I fully accept winter tyres are much better in snowy weather (though in over 30 years I've never personally got stuck without them).

But what concerns me the most is the number of people driving around (potentially at high speed) on tyres they've been led to believe give superior grip on dry roads, when in fact the opposite appears to be the case. That's why I started this thread.

It's November now and the outside temperature at midnight last night was 13.5C. If summer Contis stopped 18% quicker than winter ones at 5.5C I wonder what the difference would be at current temps?

 

[rf065]

You see I would regard not being able to stop as being more serious than not being able to start off

Exactly, and when it snows winter tyres allow you to do that.
The 18% advantage summers have in braking in milder weather becomes a minus 100% disadvantage when the snow or ice comes.

Russ

 

[Dryce]

Exactly, and when it snows winter tyres allow you to do that.
The 18% advantage summers have in braking in milder weather becomes a minus 100% disadvantage when the snow or ice comes.

Yawn. Stretch. Yawn ........

Zzzzzzzzzzzzzzzzzzz ......... o-|--<

 

[rf065]

Yawn. Stretch. Yawn ........

Zzzzzzzzzzzzzzzzzzz ......... o-|--<

This forum has really gone down hill. I think I'll call it a day for now.

Russ

 

[BTB 500]

Exactly, and when it snows winter tyres allow you to do that.
The 18% advantage summers have in braking in milder weather becomes a minus 100% disadvantage when the snow or ice comes.

Russ

But the difference is that on snow or ice you are typically driving pretty slowly. So the most likely type of accident is sliding gently into a kerb etc. (if you're not paying attention).

As opposed to bowling along at 70 on your winter tyres at 14C on a nice dry road, then finding out that they have rather less grip than you thought when something unexpected happens.

As mentioned the difference in grip for Continental summer vs winter tyres was 18% at 5.5C. At current temperatures I think it would be rather more.

 

[whitenemesis]

I know n=1 isn't a statistically valid sample but in my experience covering last year and a couple of weeks this year, I have not noticed any degradation in stopping power or grip generally over my summer tyres. Admittedly I have not had to do any emergency stops or violent manoeuvres but I feel that if there has been an 18% increase in stopping distance, I have subconsciously adapted my driving to accommodate this.

It's not as if the postulated change is suddenly there, one would easily learn the different driving/handling characteristics, as one would from one make of summer tyre to another?

 

[artyman]

Carrying some of the stats quoted on here to their illogical conclusion, would you be able to sue a driver fitted with legal tread depth Nankings as against legal tread depth Continentals because he hit you as a result of their worse stopping distance whereas had the other tyre been fitted he would have stopped. Should we all be compelled to drive the car with the best stopping distance rather than our choice of model.

 

[whitenemesis]

No, we should all drive within the limitations of our vehicle's tyres/brakes and weather conditions ...

 

[Apial]

With my cynic hat on , how do winter tyres compare price-wise?

IIRC they wear faster (due to the softer rubber compound), and have a higher recommended minimum tread depth. So you'd have to buy them more often than summer tyres if you used them permanently.

Well I get over 40k miles from a set both on an L200 and a MINI. In fact the MINI winter runflats are cheaper than the summer tyres which I find odd. And I use them permanently. The 300Ce-24 stays in the garage.