Snow chains

Hi we are driving to France for our first ski trip in years. We have been told that we must have chains but when do you use them.

You don't usually need to put the chains on, it's just that sometimes you do, so you have to have them with you (and know how to put them on!).

You only need them if there's snow on the road, and it's usually just for the last half hour or so up the mountain to the resort.

Sometimes the police will check all the cars going up and only let you through if you have snow chains on.

You might find that you need the chains even though you see cars without chains managing OK in the snow, and this will probably be because they've got winter tyres.

Chains will have to be used in the event that the signs on the road indicate so.
It's a wheel with a chain on it in a red triangle normally, and they're remotely operated so they can drop down.
You'll often find police on these roads enforcing this and if you do not have chains, you will not be allowed to continue.
Id strongly suggest getting a set of winter tyres on before you travel as well.

Depends also on the time of year and the resort you are going to...these4 are only generalisations but...
If there is any chance you may use them as infrequently as a red safety triangle and the obligatory fluorescent jackets (in france) then you may decide supermarket chain types are good enough, on the offchance. If you have an expensive car or low profle / special tyres then you can pay in the £100 range and up for a product which is designed for frequent usage and will not let you down. I took the first option, because we were going to drive to 1600m altitude on major roads except for the last 5 miles, and at Easter.
Hope this helps!!

Paul

Get The SIze

First, look at the sidewall of the tyre on your car and you'll see something like

225/45 R 18 V

this is the

tyre width in mm (225)
aspect ratio i.e. height vs width (45%)
R=Radial
wheel diameter in inches (18") and
speed rating (v=240Kph or less)

the key measurements are the wheel diameter (18" above) and tyre width (225mm above).

Check The Manual

Then look in your owner's manual or contact your garage to find out whether the wheels on your car are certified to take chains or not. For higher-performance models, you are likely to find that they are not.

In your manual or talking to your garage, they may use the term 'J' to refer to the wheel width in inches. This is the width where the tyre is fitted to the wheel.

For example, 7.5Jx18 wheel is a wheel which takes a tyre that has an inner diameter of 18" and a 'bead width' of 7.5". The bead is the bit of the tyre that fits onto the wheel and is usually slightly less then the tread width. There's a bit of leeway as to the acceptable bead width for a particular wheel width. So for example, on a 7.5J wheel (7.5") you can probably fit tyres whose bead width varies by about 1" (25mm).

The complication is that the bead width isn't usually specified on the tyre or on web pages. It will usually be a bit less than the tread width. Your local garage or tyre outlet will check this on their systems explicitly, but it's more difficult for you.

They're Certified!

If you're lucky, then the wheels and tyres fitted to your car can carry chains OK - it will say so in the Owner's Manual. So you can buy any chains and not worry.

No they're not & Why It Matters

But what if it doesn't? Take the 7.5Jx18 (7½" wide x 18" diameter) wheels above. In the manual, it may say that chains are only certified for 16" diameter wheels, not the 17" or 18" options for your car. This is because, as wider and wider wheels are fitted to your car, they consume space asymmetrically - they can't protrude outside the bodywork, so the only space they can consume is that between the wheel and the wheel arch. Compared to the chain-certified 7J wheels, my 8Jx18 wheels use up an extra 1" of around 1.5" of free space behind the wheel/tyre. What's left is perilously close to the suspension, brakes, steering if I then need another .5" with chains.

So you now have a problem. The problem is that if you attach chains to the larger wheels, the part of the chain that goes inside, behind the tyre, between the wheel and the wheel arch, may foul the suspension and brake pipes. If you are front-wheel drive, then you also have the problem that the chain may foul the steering as well.

Suppliers Patter

Beware suppliers who say "It should be OK.", or worse "You'll have to try them out first." This tells you that they don't understand or won't acknowledge this issue. Press them to guarantee that your car, plus passengers, plus luggage, plus roof-rack, doing a hairpin turn in the snow will be OK .... and you'll often find that they aren't prepared to underwrite what they're selling you. And even then, if they're wrong, the problem will be yours as you hear a terrible scrunching sound from the front suspension/steering as you drive up the mountain in the dark.

Options: Non-intrusive Chains / Winter Tyres+Wheels

There are some - expensive - chain solutions that overcome this problem. Some have no inner components at all, and some have very thin elements that only add 2-3mm which should be OK.

Which leads me to mention Winter Tyres. But that's for another posting ...

Remember, this isn't a matter of whether you can get past a bolshie French Gendarme at the snow chains sign. It's a matter of getting the right accessory that in the snow will (a) work properly and (b) not destroy your car's drivetrain and (c) not invalidate a car insurance claim if you have an accident while they're fitted.

Hope it helps. As I said, first thing, check your tyre spec and look in the owner's manual. You may have no problem.

Here's the problem with chains, and why winter tyres are so good. Even for UK winters.
___________________________________________________________________

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.

fantastic posts ...admin ought to make it a sticky!
ps I have my snow-tyres on already...

We have winter tyres - but then again we drive to the slopes at least once a month in the ski season. My one tip is to actually try putting on the chains in the luxury of your own drive. Last season of the six trips we did to the mounains chains were required on four of them (by the police! ). The number of people who were standing at the side of the road looking perplexed at how exactly to put them on (they are not easy!) and the number of chains that fell off was astonishing! Even with winter tyres we carry snow chans but usually don't need them!