Msej449
reply to 'Composite 'Snow Chains' by Michelin' posted Dec-2014
I was being asked so often about this by colleagues and relatives that I wrote some thoughts up as follows:
The scenario ….
You're driving along a French road on the way to skiing in the Alps. Outside, the temperature is around 0°C to -2°C and the skies are grey. "We're fine – the snow chains are in the boot, so we're prepared. And we're front-wheel drive anyway." you say.
But you are already at a disadvantage against the French and German cars around you. They have their winter tyres on and you're on the summer tyres fitted as standard to all British cars. This means that when you brake, you'll take 20%-25% more distance before you come to a stop, even on tarmac. Now it starts to snow and after a while you're driving through patches where you're alternating between tarmac and snow. But you can't stop easily and anyway, the chains aren't suited to this. "If it gets heavier, I'll put the chains on – but no one else is, so let's see. I can't keep putting them on and taking them off."
The car starts to slide a bit on the snowy patches and you slow down to compensate, but everyone else seems to be coping fine. That 25% difference in stopping distance is now more like x2-x3 but it's not obvious. And there's a queue building up behind you. "Can't these people see it's snowing?" In fact they can, and since this is a regular winter situation, that's why they have their winter tyres on. They don't need to slow down until the conditions are much worse. And it looks like they're behind a typical English driver who seems to think that having chains solves everything.
Snow now covers the road, but it's not that deep and you're debating whether to stop and put the chains on when you approach a corner and slight incline. Each car ahead happily takes the corner at 50Kms/hr but when you do the car slides alarmingly. You just about keep it on the road but halfway up the incline (it can hardly be called a hill) you gently glide to a halt, skewed slightly into oncoming traffic, the wheels spinning. Further back in the queue, another English car coasts gracefully into the rear of a French delivery van and at the corner, a similarly unprepared young Dutch driver pitches quietly into the ditch. Your chains are still in the boot.
Q&A
Question: What are the ideal wheels in winter conditions?
Answer: Narrower and smaller-diameter wheels, with winter tyres to match and chains for the worst-case conditions.
Question: Is a 4x4 best for snow?
Answer: I'd rather be in a Ford Ka with winter tyres then a BMW X5 with summer tyres. The Ka will be able to negotiate conditions that the X5 can't cope with.
Question: What about just having chains?
Answer: Better than nothing, but not as good as having winter tyres and chains. While the locals will be driving round as normal on snow with winter tyres and no chains, you'll be sliding-round getting stuck, or worse, won't make that corner they have easily driven round. And in mixed tarmac/snow conditions you can't be taking your chains on/off all the time.
Question: If I have winter tyres, do I still need chains?
Answer: Yes! For deep snow, steep inclines and ice, you will still need chains.
Question: Do all four tyres need to be winter ones?
Answer: Yes. Don't mix winter and summer tyres.
In Alpine areas, and many parts of mainland Europe, the norm is to swap to winter tyres in winter. Chains are a last resort for short periods where the conditions are just too difficult for winter tyres alone. Where you get mixed tarmac and snow, winter tyres also have the advantage.
Tyres
Winter tyres are designed to operate at lower temperatures. They begin to perform better than standard tyres at temperatures below around 7˚C. They offer up to 30% shorter stopping distances on tarmac - the compounds make for better adhesion at lower temperatures. The tread design will also provide much better traction in the slush and snow:
My winter wheels and tyres are 10mm narrower then the summer ones. This is so that when chains are fitted, they don't foul the suspension, brake, drive or steering bits on the inside of the wheel arch.
The premier manufacturers of winter tyres are Michelin, Pirelli, Vredestein and Continental, all of whom have a range of winter tyres for different types of vehicles and extremity of conditions. Details are available on their websites, which you should use to discover your local specialised dealer for winter tyre advice and fitting.
In theory, of course, fitting winter tyres doesn't cost you any more overall, as you prolong the life of the summer tyres by a corresponding length of time. In reality, you have to pay for switching them over every spring and autumn plus the up-front cost of the tyres themselves.
If you're lucky, you may have suitable wheels already fitted. In which case you can just get the tyre dealer to fit winter tyres and swap them each autumn and spring. This is the case on our little Peugeot 206. However, for my Audi A3, I've had to buy a separate set of winter wheels that are 10mm narrower than the summer ones fitted as standard as chains just wont fit the bigger wheels.
Studded tyres are only used in Nordic countries where you are driving permanently on snow and ice throughout the winter. They're not relevant for UK or Alpine driving.
Wheels
Look at the Owner's Handbook and you will find that in many cases, it explicitly excludes the wheels fitted to your car from being capable of taking chains. Take a look and see, or ask your dealer.
To check for yourself, you'll need to find (a) the tyre size and (b) the wheel size.
First, look at the tyre wall and record the specification numbers e.g. 225/45 Y 18 with the last digits [18] being the wheel diameter in inches, and the first digits [225] being the width in mm. Here are the details for my car:
Wheel: '7.5Jx18' - Tyre: '225/40-Y-18' = 225mm x18" - Summer
Wheel: '7Jx17' - Tyre: '215/45-Y-17' = 215mm x17" - Winter
The Owner's Manual may state the wheel size using the letter 'J' 'e.g. '7.5J x18' above means it's 7.5" wide and 18 inches in diameter. The winter wheels are 7Jx17 i.e. 7" wide and 17" diameter.
The 18" wheels that are standard on my A3 are not certified to carry chains - it's unlikely that there's enough space (between tyre and interior gubbins) to accommodate them. So my winter tyres are on smaller 17" wheels which carry 215 tyres - 10mm narrower. This provides the extra space taken up when the chains are fitted.
On our Peugeot 206, however, the standard wheels it carries are certified for chains, and so we only swap tyres round. We use the same wheels summer and winter, and alternate between winter and summer tyres.
Chains
The main problem with chains is that when you fit them, the bits of the chain that wrap around the inner side of the wheel can foul the suspension or steering.
On my A3 with standard (summer) wheels and tyres, there's about 30mm of free space between the tyre and the bodywork, suspension etc. Even the thinnest chains need 10mm or so of free space, and cheaper ones may need up to 25mm. If you have bigger wheels on your car, then it may be that there isn't enough free space for chains to be used safely.
Beware chain retailers who either don't mention this problem or say "It should be OK." or "Try them out first." Clearly, you can't really try them out for real, and anyway, what if they do cause some damage? Remember, the issue isn't with the thickness of the chains as such, it's whether there's enough room behind the driven wheel/tyre – especially if its front-wheel-drive. In most cases, retailers haven't got a clue. Chains that seem to fit when you "try them out" on your drive in the summer may cause damage when you're driving round a hairpin bend, fully-loaded, with four passengers and a roofbox. Or perhaps they don't, and you then have to garage the car for repairs ☹ Great.
Look in your Owner's Manual and see if your wheels are certified to carry chains. For example, my A3 can carry 16", 17" or 18" wheels, with the latter not certified to carry chains.
There are lots of different chains designs and manufacturers. I use Michelin 'Easygrip' (see Michelin.co.uk) on our home Peugeot because they are relatively easy to fit; are relatively thin (<10mm); and don't need re-tightening after initial fitting. However, they are not really for prolonged use – more to get you out of a tight spot when your winter tyres can't cope. On the other car that goes down to the Alps, we carry conventional metal chains, which are better if you have to drive for any distance (although you then have the clearance problem, obviously).
Be Prepared: Fitting chains outdoors, in the snow, at night can be a nightmare. It will help if you carry a mat to kneel on, torch and gloves and have them to hand along with the chains. Try fitting them at home first. If it snows at home, it may be worth trying them out.
Incidental Advice
Screenwash: If you're going on a long journey in winter, especially down to the Alps, completely empty the reservoir, pipes and nozzles of any diluted screenwash and refill with 100% concentrate. Otherwise the pipes and nozzles will freeze.
Boots: Also have a spare pair of boots to hand when driving, so you can go out in the snow and change back into dry driving shoes when you return.
And as mentioned above, have a torch, a mat and gloves handy as well - not buried somewhere under all the luggage. And if it snows at home, take the opportunity to try chains out under more benign conditions
Edited 3 times. Last update at 16-Dec-2014
