Techniques

Snow chains – front or rear on your 4X4, or not at all?

An easy way to start a debate is to ask whether snow chains should go on the front or rear wheels of a 4X4.

FIRST LET’S dispense with a myth, which is that you don’t need chains if you have 4WD, or mud tyres, or extreme tyres, or 35-inch tyres. That’s completely wrong.

Chains turn worn road tyres into amazing grip devices than can beat new mud tyres, because chains bite down into soft surfaces in ways that rubber tyres can’t manage. I have been in several situations where my mud-tyred vehicle couldn’t make it up a snowy hill with momentum and aired-down tyres, yet fit one set of chains and up we go in first low at idle. And last weekend we had a car with 37″ tyres unable to move, on the flat, because it had got itself into a slightly-off camber situation where there was some snow built up at each wheel. The tyres just spun on the snow, compressing it into ice, whereas with chains the tyres can bite and grip.

The difference is stark, like driving up a sand dune at 15psi as opposed to 40psi. Chains are a benefit as soon as there is snow on the ground, not just when you’re battling through half-metre drifts.

So chains are great for snow traction, but front or rear fitment? The answer is the same as many 4X4 “what do I do” questions, and it is “depends on the situation; terrain and the vehicle.”

Defender in deep snow on a hill. No way that would be driveable without chains…I tried!

The terrain may be uphill, downhill or on the flat. Those hills may be really steep, or quite gentle. The terrain may be icy, hard ground such as frozen snow over bitumen, or deep, soft, fresh snow on earth. There may or may not be ruts for your wheels to follow, and may or may not be undulations where wheels lift in the air.

The vehicle is a factor too. Whether you have a front or cross-axle differential lock will influence your choice too, as will whether your vehicle has an on-demand all wheel drive system, and all that considered in context of the terrain.

Not a lot of clearance.

Finally, you may well be limited to whether you can fit chains at all, or limited to the rear wheels only.  One thing is clear though – four chains are always better than two!

So with those caveats, let’s look at some pros and cons of front vs rear axle fitting:

Pros of a front chain fit

  • More steering control is retained as the front tyres can grip
  • Better braking as there is a weight shift to the front when braking
  • Generally more controlled descents due to better steering and grip on the front

Pros of a rear chain fit

  • Better hill climbing ability as there is a weight shift towards the rear
  • Under braking you will understeer if the front can’t grip; this may be better than losing the rear end sideways

Which to choose when?

In Australia, my snow driving is usually on 4WD tracks with moderate gradients as the really hard ones are closed for winter. In those situations, I prefer chains on the front wheels. I have found that front-chained 4X4s do a good job of climbing moderate snowy hills, and are effective when braking as there’s a weight shift to the front so there’s less need for traction on the rear. As I only fit chains in deepish snow there are also snow ruts which mean the rear wheels can tramline, unlike say driving on ice-covered roads where you’re basically on a skating rink. And in tight turning situations the extra grip on the front axle is welcome too.

4WDs can generally drive through snow like this, but once it gets a little deeper and steeper chains come into their own.

However, my Ranger won’t take my chains on the front axle, so I’m limited to the rear. There is another advantage to the rear fitment and that is the Ranger’s rear cross-axle differential lock. Chains don’t help when one wheel is in the air spinning, and in fact wheelspin is to be avoided at all costs with chains. With the rear locker in then if one wheel is off the ground the other drives the vehicle forwards. The Ranger has limited axle flex compared to say my Defender, so it is more likely to lift a wheel.

If your vehicle is an all-wheel-drive softroader with one of those on-demand systems that mostly drive the front wheels then always fit chains to the front if they will fit. This is because the 4X4 system is not designed for continuous use in 4X4 mode, and the centre clutch can overheat leaving the car in 2WD (front drive) until it cools down. With the chains on the rear that’s likely to happen as the rears start to do a lot of driving work. Yes, there may be a ‘Lock’ button, but trust me, that’s marketing not engineering.

There is an argument that fitting chains on the rear is better for descents, on the basis that you don’t want the rear to overtake the front. There is some merit in this argument, but the counter is that you’ll get better braking and traction from the front axle due to the weight shift to the front. Consider an off-camber descent; if the chains are on the front the rear wheels may slip down and sideways, and vice-versa if the chains are on the rear.

The correct response would be to anticipate the problem and fix it with track building, traction ramps or lower down with a winch, but in the absence of those options front chains work better. This is because there’s more weight on the front wheels and thus better traction, and the front wheels need to steer and grip sideways, whereas the rears only have to grip sideways. But sliding one axle sideways off-camber is generally going to end in trouble regardless of your chain choice, which is why not driving into those situations and fixing it before you get there is the smart thing to do.

A test fit at home…
…because that makes this easier.

So when it comes to chains front or rear, there is no “always” answer to this question, and if there was it wouldn’t come up for discussion so often. It’s not like the benefit of airing down for sand where there is no debate, or the use of low range in rocks.

What you have to do as 4X4 owners is the same as always – understand the concepts from first principles, apply your understanding to the situation, drive while constantly evaluating your situation and be prepared to try something else. But regardless of the axle you fit your chains to, they’ll make a huge difference in deep snow.

Snow chain tips

  • Check your manual – can you fit chains, and if so, on which set of wheels?
  • Fit at home first – chain fitting is not easy and you do not want to learn in the cold, snowy mud.
  • Check fit every time with new vehicles and tyres – tyre diameters and sizes do vary a bit, and you need to check clearances. Even if you know how to fit chains, check again with every new vehicle or tyre.
  • Go slow – chains offer so much traction there is no need for speed, and they are not designed for speed either.
  • Remove when off snow – don’t chew up the tracks for no reason.
  • Buy quality – never, ever skimp on 4X4 gear and especially not chains. They can last for decades if cared for, and if they come off then you have serious damage do your vehicle.
Sometimes you just need to winch!


Robert Pepper

Robert Pepper

Robert Pepper is the editor of PM4x4, an offroad driver trainer and photographer interested in anything with wings, sails or wheels. He is the author of four books on offroading, and owns a modified Ford Ranger PX which he uses for offroad touring. His other car is a Toyota 86 which exists purely to drive in circles on racetracks. Visit his website: www.l2sfbc.com