Tire World's Tech Tips (8)

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Traction on Ice and Snow

4-wheel drive is often an after-thought. We usually don't think about it until it's needed.

The roads are slick. Snow is blowing. Warming the car, you pull the lever for the 4-wheel drive and . . .

Then again, it may happen when you're on the road. It starts to snow. The roads get worse. You're still too far from home. You push the 4X4 button and nothing new happens or, once the 4-wheel drive engages, ominous sounds begin.

Unfortunately, you cannot tell until that moment if the system is in good working order but you can ask Tire World to test drive your vehicle and check it.

Consult your owner's manual. Generally, the components of this system should have their fluids changed every 15,000 to 30,000 miles.

In most vehicles, this would mean changing the oil in your front and rear differentials as well as the transfer case. Getting the transmission oil changed then is a good idea, too.

The differentials are the equipment on each axle where power from the engine is directed toward the wheels.

The transfer case, usually located on the side of the transmission, is what is engaged when the 4X4 button is pushed or the lever is pulled. This allows power to be directed to the two wheels that do not normally receive power.

There are numerous ways that power is directed to the wheels to drive your vehicle. The oldest is rear-wheel drive. This has the effect of pushing your car forward using power from the rear wheels. In this case, the front axle is not engaged until the vehicle is put into 4-wheel drive (if equipped). Then the front axle becomes the more important of the two, since the front generally carries most of the weight.

Many of us know how rear-wheel drive acts on ice. Push on the gas and the back end will "fishtail" due to the rear wheels spinning, attempting to get traction.

4-wheel drive was developed in the WW2 era to get vehicles through sand, mud, snow and such. Older 4-wheel drive systems required you to manually lock/unlock the wheel hubs before engaging/disengaging the 4-wheel drive system. Newer systems allow you to make these changes from the warmth of your driver seat.

On most vehicles equipped this way, the right rear wheel and the left front wheel do most of the work but all 4 wheels are able to pull or push the vehicle. Recent developments, as in the Jeep Rubicon, have sensors to tell which wheel has the most traction, sending power to the wheel(s) most able to work. This enables the vehicle to move even if only one wheel has traction.

Next, front-wheel drive was developed. This has power going to the front wheels only, which gives the effect of pulling the car forward. Front-wheel drive is more stable when there is insufficient traction. The fishtail motion is eliminated.

All-wheel drive sends power to all 4 wheels. You don't have to make any changes if road conditions deteriorate but there is no option to decrease the number of wheels that get power - an option that may improve driving efficiency and lesson wear.

In adverse conditions, 4-wheel drive (or all-wheel drive) will
1) Help you to get moving and
2) Increase your directional stability. That is, once you are going in a straight line, it will help you stay that way.

This doesn't mean you can fly around corners and still hug the road. It also doesn't mean you can stop any better than if you had power to only 2 of your wheels.

To improve your ability to stop you will need studded tires or chains.

Now that you navigate the roads more safely in your properly equipped, well-maintained vehicle, you will need to know if there is anything special to returning to 2-wheel drive. In some vehicles, you will need to take them out of 4-wheel drive and drive in reverse for a bit in order to disengage the mechanism. Consult your owner's manual for this or ask Tire World about your specific requirements.

Have a safe winter.

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