There are many factors that make the difference between being stuck in snow and getting through, the main ones being depth and condition of the snow itself. It follows that the deeper the snow, the more likely you are to have problems, but, as we said earlier, the temperature also affects how the snow behaves. A few centimetres of snow at temperatures close to freezing may result in a very slippery surface that brings everything sliding to a halt. But many more centimetres of dry, deep frozen snow may be easy to drive over, though it depends how it compacts down: deep soft snow that compresses a lot, like a windblown drift, may leave the car laying on a pillow that lifts the wheels off the ground.
Other factors in getting stuck include:- the depth and pattern of the tyre tread- tyre inflation- how you use the throttle- the angle of the road- how much room for manoeuvre you have.
Tire tread:- If your tires are badly worn, don’t expect them to grant grip in snow. A deep, blocky tread generally provides the best grip, which is why off-road ‘mud and snow’ and winter tyres are generally like that. The smoother treads designed for high performance cars may grip well at speed in the wet, but not in snow, so take care. In places where it snows heavily and winter temperatures are very low, drivers often have a set of winter tyres fitted which have a read pattern suited to snow and are made of a rubber compound that stays relatively soft in low temperatures.
Tire inflation:- Tires generally grip best if they are inflated to the pressure suggested by the car manufacturer. The only exception to this is that in very deep snow you may get extra grip by lowering the pressure to allow the tread to flex more. However, this should be an emergency procedure only and you should return the tyres to their normal pressures as soon as possible.
Throttle use:- A driven wheel loses grip when you try to pass more power through it than the tyre can transmit to the road, which is easy on snow and ice. Therefore, once a wheel has started to spin, there is usually no point m applying more power. In fact, if the wheel spins in deep snow, it digs itself in and may also help polish the icy surface underneath.
In addition, any driven axle has a system of gears called a differential (diff) which allows one wheel to turn faster than the other to make up for the differences in distance travelled by the inside and outside wheels on a turn. So, when a wheel spins, the diff is fooled into behaving as if that wheel needs to turn faster than the other, so all the power goes to that wheel. That means you may only have one wheel in trouble, but the one that could move you is getting no power. In those circumstances you will stay stuck unless your car has a limited slip diff, which only allows a portion of the power to go to the spinning wheel, or an electronic traction control system which will brake the spinning wheel.
Always use the throttle smoothly on slippery surfaces. In snow, if you suddenly add or take away power you can make a wheel that was managing to drive you lose grip. This can also seriously affect the car’s handling, making it skid. So, on snow and ice you must always be gently on and gently off the throttle. Use the brakes very carefully, especially if your car does not have ABS.
Angle of the road:- It is obvious that if you need to climb a steep hill in snow and ice, you have a problem. What is not so obvious is that gentle slopes can also cause difficulty. This is particularly so in snow at around freezing point, which is why it can create such difficulties in towns where the temperature is a bit higher than in the colder countryside. Only start climbing a slope if you have plenty of room because if you lose grip you will slide to one side. If you can’t get up the slope, try to select reverse to come back down, so you retain control.
If you have to come down a slope, select first at the top and let the car run down with your foot off the throttle. This will allow the engine to slow you down with less risk of locking the wheels and creating a skid. If your car has ABS you may be able to use the brakes to slow you further, but be careful because some ABS systems do not work at very low speeds.
If the car starts to slide on a downhill slope, you may be able to regain control by gently applying the throttle. The car is sliding because its forward speed is faster than the wheels’ rotational speed so by applying the throttle, especially in a front- or four-wheel drive car you should be able to match the wheels’ rotational speed to the forward speed and regain some steering control.
Camber and other danger signs like this can also cause problems when it is slippery. On a steeply cambered road the car may start to slide down towards the kerb. Easing off the throttle may return grip. Avoid trying to steer back up the slope because this gives the front wheels even less grip. You may get steering control back if you ease the steering towards the direction of the slide. Unfortunately, you generally have little nine or space to do much about it.
Room for manoeuvre:- You need space to counter the effects of slippery surfaces, so think carefully before entering a restricted area. Only go in if you can drive straight through: so do not enter, say, a narrow bridge until the car in front has got through. In two-way streets, don’t try to pass through gaps with someone coming the other way. If you wait for the other driver to pass it means there is only a risk of one car sliding and any resulting impact will be lessened. In addition, if they slide into your stationary car, it’s their fault not yours.