Only Buying Two New Tires? Put Them on the Back.

After winter is over, many people will take their vehicles to the local auto shop to buy new tires. The front tires wear faster than the rear tires since the majority of the braking is directed to the front tires, which is why there is so much more brake dust in the front rims. Because of this, often it is necessary to only replace two tires that are worn. For some, buying a set of four new tires is simply too expensive, so they opt for two new tires instead. In general, people take the tires for granted and do not understand that that car uses all four tire to turn, not just the front two.

Many tire dealers erroneously encourage car owners to put the two newest tires on the front of the vehicle and move the two older tires to the back. Among other reasons, they believe that it is easier for drivers to control a blowout in a back tire than it is in a front tire.  More often, both the tire installer and the car owner falsely but in good faith believe that better tires on the front give better steering.  Those who understand handling dynamics of automobiles know that such knowledge is not only false, but on a wet road could prove disaterous.

Putting the new tires on the front of your vehicle, however, is the wrong move -- and can be a fatal mistake. Rather than making the car more stable, new tires on the front and leaving worn tires on the rear will have just the opposite effect on a wet road surface, and cause you to lose control of the vehicle.

Correct New Tire Placement

Today's cars and trucks were designed to under-steer in order to accommodate inexperienced drivers who tend to slam on the brakes when they go into a turn to fast. A car that is not turning as much as the driver intends is descibed as understeering or "straightening out the curve." Understeer is easy to control, and the intuitive response is to apply brakes to slow and cranking in more steering to stay on th eroad.  This is the proper response, and the braking puts more weight on the front tires which gives them more of a bit and the rear tires follow the fronts around the curve.  Putting new tires are put on the front of the vehicle instead of the rear,  defeats this purposely designed in under-steering tendency in vehicle and turns it into an over-steering monster.  Oversteer is where the rear end breakaway first when going into a turn to fast, or after an emergency evasive maneuver.  Typically, oversteering is called "fishtailing" and is best idenified as the rear end going out of control.  Since the rear tires must have enough traction to follow the front tires around a turn, if the rear tires lose traction the car just follows the physics of the road surface out of control.  Most drivers do not know how to recover from this situation and a crash or going off the road sideways or backwards, or into opposing traffic is unaviodable.

Here's how: if a car has little tread on the rear tires and new tread on the front tires, then the car is going to be more prone to fishtailing on wet surfaces because the rear tires will not be able to gain traction on the slippery road. Once the car goes into a fishtail, then the car will automatically over-steer in an attempt to regain control. However, in these cases it will be very difficult if not impossible for the driver to regain control over the fishtailing vehicle. As a result, the driver will be more likely to be in accident, whether from colliding with another car or going off of the road.

Depending on the speed the car was traveling and other factors, these types of accidents can be catastrophic. The driver and any occupants in the vehicle may suffer very serious injuries from incorrect tire placement, including amputations, paralysis and permanent disability.
The dangers of incorrect tire placement are well known. The major tire manufacturers have included instructions in their guides for years that instruct tire installers to put the two newest tires on the back of the vehicle rather than the front. Additionally, there have been several studies, investigations and lawsuits that have uncovered the potential harm that may be caused by incorrect tire placement.

Conclusion

It is important to have good tread depth on your vehicle's tires, especially when you are driving on wet road surfaces. The best way to maintain your tire's tread depth is by regularly checking your tires and replacing them when the thread depth falls below 4/32'.
If you cannot afford to replace all of your tires at the same time, remember that you should have the two newest tires placed in the rear, rather than the front -- even if the mechanic tells you otherwise. This one small move can help you avoid becoming a victim of a rainy day accident.