Wheel spin in snow/ice

[martine]

I live at the bottom of a mild hill at the end of a close. In common with most local roads, our close has a nice covering of compacted snow (i.e. ice) and it's been difficult to get up the hill in the mornings. My Focus ST has more tendency to wheel spin than our Previa people carrier...so 2 questions:

1) why is this? They are both front-wheel drive, the ST has fatter tyres and weighs less - so I'm guessing less grip in this situation or is it something else?

2) Someone said it's better to reverse up a hill - is this because of weight transfer onto the driving wheels (on a FWD)?

[Porker]

I suppose it could be any of a number of reasons Martin but I would guess that the ST's tyres play a large part. Optimised for warm weather grip, handling and longevity (to a degree) they're possibly just a lump of frozen rubber at 0 degrees Centigrade. Your other car's tyres may be more compromised for warm grip but offer better cold weather grip.

Having sought out 130 miles of the iciest, most snow-covered roads in Essex, Cambridgeshire and Suffolk on Saturday in the company of Gareth and his snow-tyre-equipped daily driver, you may be assured that I have a new-found and very marked respect for the abilities of dedicated winter tyres.

regards
P.

[TripleS]

Is compacted snow the same as ice? I wouldn't have said so. To my mind the situation is basically this:

First we get undisturbed snow, which we can drive on reasonably well, so long as the depth isn't sufficient to stop us. When this has been driven on it becomes compacted but it still isn't particularly hard, so at this stage it will also have visible tyre tread marks, and these can give us a bit of extra grip, compared with what we encounter at the next stage.

The next stage is when this compacted snow has been driven on by more vehicles, such that the surface becomes harder and no longer shows tyre marks. In this condition the surface still looks white, and the increased hardness now affords us less grip, but I still don't call it ice.

The next stage is when this surface has had yet more traffic on it, with the result that the hardness increases further, and the surface has acquired more of a polished nature. This reduces the level of grip a good deal further, and things are now getting rather more difficult. By this time the surface will be looking grey in colour and the nice bright whiteness has gone. This is the stage at which I call it an icy surface, but I apprecaite others may apply that term earlier.

The final stage is where this hard polished icy surface acquires a film of water on top, and it is at this point that I feel it's time to park the car and crawl to somewhere safe on hands and knees. I kid you not: I've long been very nervous of walking on icy surfaces (it isn't just an age thing) and I have got even worse about this. Although some people find it amusing to see people falling on the ice and landing on their bum, it's not actually funny. At the very least they get a bad shaking, and there is always a risk of breaking something, especially in the case of an elderly person. Much earlier in my driving career I used to get irritated to find people walking on the road rather than on the pavement, but not any longer; I now understand their anxiety all too well.

Anyhow, getting back to driving, I don't mind fairly difficult conditions, but I would say this final stage surface is virtually impossible to cope with - unless somebody comes alomg and tells us that a good set of winter tyres will give us a sporting chance. Maybe that's the case, maybe they will help us significantly, but otherwise I would call a halt at this point.

Best wishes all,
Dave.

[Gareth]

unless somebody comes alomg and tells us that a good set of winter tyres will give us a sporting chance

See Porker's posting immediately before your own

[TripleS]

unless somebody comes alomg and tells us that a good set of winter tyres will give us a sporting chance

See Porker's posting immediately before your own

Yes, I did see that, but do they really do much better on the hard, polished wet ice? That is the surface I was particularly concerned about. It is possible that they are still a benefit, but I was inclined to feel that nothing short of studded tyres would really make much difference on that sort of surface. I may be wrong.

BTW, what sort of winter tyres are you using, and how did you arrive at your choice?

Best wishes all,
Dave.

[Gareth]

do they really do much better on the hard, polished wet ice?

Tirerack have some interesting practical tests that demonstrate advantages of winter tyres in various conditions. The link goes to some comparative tests on an ice-rink, and there is a video that's worth watching as well.

I've saw other videos on that site that amply demonstrate the advantage to fitting winter tyres to all four wheels, so that's what I did.

what sort of winter tyres are you using, and how did you arrive at your choice?

Vredestein Snowtrac 3 - I chose this particular tyre after reading that Vredestein are consistently marked near the top in German winter tyre testing, and perhaps rather fortuitously as I have since read that British winters are more akin to mid-European winters typically being wetter than Scandinavian winters, (and consequently requiring different tyre characteristics).

I picked the narrowest tyre / smallest wheel combination recommended by the manufacturer, ordered steel wheels in that size then picked the higher speed rating tyre, so I have H-rated winter tyres instead of the standard V-rated summer tyres on a car that anyway can't go faster than 129 mph. Incidently the wheel / tyre choice resulted in less unsprung weight!

[fungus]

The old Saab 96 ran on narrow tyres and was an extremely sucessful rally car back in the 1960s, seeing off many of its' more powerful rivals, especially in the snow.

Dave is correct that the roads/pavements are at their most slippery when the thaw is starting and there is a thin layer of water on top of the ice. My wife walked to the local Co-Op on Sunday as it was just starting to thaw and slipped a couple of times, one young lad in front of her ending up completely on his back.

[TripleS]

do they really do much better on the hard, polished wet ice?

Tirerack have some interesting practical tests that demonstrate advantages of winter tyres in various conditions. The link goes to some comparative tests on an ice-rink, and there is a video that's worth watching as well.

I've saw other videos on that site that amply demonstrate the advantage to fitting winter tyres to all four wheels, so that's what I did.

what sort of winter tyres are you using, and how did you arrive at your choice?

Vredestein Snowtrac 3 - I chose this particular tyre after reading that Vredestein are consistently marked near the top in German winter tyre testing, and perhaps rather fortuitously as I have since read that British winters are more akin to mid-European winters typically being wetter than Scandinavian winters, (and consequently requiring different tyre characteristics).

I picked the narrowest tyre / smallest wheel combination recommended by the manufacturer, ordered steel wheels in that size then picked the higher speed rating tyre, so I have H-rated winter tyres instead of the standard V-rated summer tyres on a car that anyway can't go faster than 129 mph. Incidently the wheel / tyre choice resulted in less unsprung weight!

Many thanks for that, Gareth.

At the moment I'm not convinced that my pattern of car usage merits the use of winter tyres, but if I do anything it will be primarily in the interests of better traction for the front wheels for getting up gradients, so I'll probably leave the rear ones alone. I'm not too concerned if this produces a bit more tendency to oversteer.

FWIW my normal tyre size is 195/65 x 15 and I don't think I'd be inclined to change from that. I understand that wide tyres are considered to be detrimental in winter conditions, but I wouldn't have thought it worthwhile to seek narrower ones in this case, especially if they require different wheels.

Best wishes all,
Dave.

[waremark]

At the moment I'm not convinced that my pattern of car usage merits the use of winter tyres, but if I do anything it will be primarily in the interests of better traction for the front wheels for getting up gradients, so I'll probably leave the rear ones alone. I'm not too concerned if this produces a bit more tendency to oversteer.

I'd love you to try, and report back. You might be amazed by quite how unstable the car becomes with a lot more grip at the front than at the back. On the Volvo courses, they put winter tyres on the front and summer tyres on the back of a couple of cars. They were called (technical term) the 'wibbly wobbly cars' and on the ice they would go very sideways at ludicrously low speeds. Great fun and good steering practice, but not ideal for the road. On the other hand, using chains on a front wheel drive car, it would be normal to put the chains only on the front: so obviously if you go slow enough in relation to the available grip you can keep safe.

[TripleS]

At the moment I'm not convinced that my pattern of car usage merits the use of winter tyres, but if I do anything it will be primarily in the interests of better traction for the front wheels for getting up gradients, so I'll probably leave the rear ones alone. I'm not too concerned if this produces a bit more tendency to oversteer.

I'd love you to try, and report back. You might be amazed by quite how unstable the car becomes with a lot more grip at the front than at the back. On the Volvo courses, they put winter tyres on the front and summer tyres on the back of a couple of cars. They were called (technical term) the 'wibbly wobbly cars' and on the ice they would go very sideways at ludicrously low speeds. Great fun and good steering practice, but not ideal for the road. On the other hand, using chains on a front wheel drive car, it would be normal to put the chains only on the front: so obviously if you go slow enough in relation to the available grip you can keep safe.

OK, if I do anything at all it will be fronts only, at least intiially, and I'll see how I feel about the result, before deciding what else to do. Apparently it is not universally accepted that it needs to be winter tyres all round: according to what I've read there are still conflicting views on this. There should be room for differing attitudes, because the overall effect will depend on what tyres are fitted at the front, compared with the rear, and indeed the vehicle used, and the driver's inputs and style will also have a bearing on the success, or otherwise, of what is done.

Best wishes all,
Dave.

[Gareth]

if I do anything at all it will be fronts only, at least intiially, and I'll see how I feel about the result, before deciding what else to do. Apparently it is not universally accepted that it needs to be winter tyres all round: according to what I've read there are still conflicting views on this.

If you never brake into corners and never brake mid-corner and generally don't push too hard, I think you would probably be OK but I'm not as knowledgeable about this as others who have posted here. From what I understand, though, when the back goes it goes pretty quick and well beyond my capabilities to catch.

[SeanP]

I have a new-found and very marked respect for the abilities of dedicated winter tyres.

Likewise, after visiting some colleagues in Trondheim, March last year - when we had our last 'big fall'; it was also 'abnormal' in Trondheim (2-3ft of snow in the same period!). Though they're very well prepared and clear main routes (and keep them clear), they just don't bother with car-parks and smaller side-streets.

But Winter tyres are mandatory, and driving around frozen car-parks, up steep icy roads etc., at a more-or-less 'normal' pace and without incident (or much risk of any) was very refreshing (though unnerving at first!) and shows just how well a decent set of rubber designed for the condition works very effectively!

Studs are optional - with a higher tax-band if used (to pay for damage to road surfaces etc.).

Hence, if snow / icy conditions are to be the norm for 'global warming', then I shall seriously consider a second set of wheels with winter tyres to allow myself to remain mobile!

[Gareth]

if I do anything at all it will be fronts only, at least intiially, and I'll see how I feel about the result

Here is a tyre test video that demonstrates the potential dangers with this approach. This is number 2 in a series of 4 videos, and it is worth watching the others as well.

[TripleS]

if I do anything at all it will be fronts only, at least intiially, and I'll see how I feel about the result

Here is a tyre test video that demonstrates the potential dangers with this approach. This is number 2 in a series of 4 videos, and it is worth watching the others as well.

Once again thank you for that reference, but I am aware of the potential dangers of that approach.

I don't doubt there is a fair measure of valid stuff in that video, but to me it has a feel of sales talk, so I maintain a degree of scepticism about some of it. When somebody says (about 4:55) that summer tyres at low temperatures are as hard as iron, that's merely being silly and it makes me disinclined to respect the rest of what they say. Call that pedantic if you wish, but when people make glib statements like that, their utterances tend not to wash with me - as somebody else said recently on another topic. I think they weaken their own case by doing that.

I will have a look at the other three videos, but if I'm to be pushed in the direction of having all four tyres alike, then based on the conditions I've encountered so far, they will be what I've already got.

No doubt some will feel I'm being 'difficult' about this subject, but in that case they should have more concern about all the millions of drivers out there who are not even aware of the tyre situation that has been engineered for us, and they, therefore, are in an even worse position than me. I think there is much more danger there, because they are not even thinking about this subject and they are unaware of the extent to which they are being disadvantaged.

At the end of the day the probability is that I shall decide what to do based on my own experience and judgement, and if that is not a reasonable approach, that E and J is worthless.

Best wishes all,
Dave.

[Octy_Ross]

I think there is much more danger there, because they are not even thinking about this subject and they are unaware of the extent to which they are being disadvantaged.

I thought this, this morning, that I was glad I didn't have the grippy stoppy tyres as the guy behind would never be able to stop in the distance I could .... so if I did use the brakes I'd be bound to brake no faster than the muppet behind anyway!