Tire rotation. We’ve all heard of it, but so few of us do it regularly. And, when we do, we are seldom certain how it should be done. The guy at the fast-lube shop may recommend one pattern, and your owner’s manual suggests another.
Some people think that rotating their tires is a waste of time. Others say it’s a scam to make them wear out at the same time so the tire store can sell four, instead of two, new tires. Besides, what’s the big deal about ignoring tire rotation?
There was a story in a recent issue of Motor Age, a trade magazine for professional technicians.
Larry Hammer, the technical expert for Mighty Auto Parts, an automotive parts distributor, tells about a guy who was having trouble getting his boat and trailer up the ramp. The wheels were spinning, so the guy put his Ford Ranger in four-wheel-drive and, sure enough, up the ramp they go. But the guy could not get his Ranger out of four-wheel-drive, and drove it home, slowly, in four-wheel low.
The next day, the repair shop diagnosed the problem as a bad control switch on the dash, which was replaced. The truck seemed fine as they check it out on the lift, but once it was on the street, it was stuck in four-wheel-drive again. After several more attempts to fix it, the technicians were stumped. Nobody had thought to check the tires before they called the help hot line.
One of the tires was a replacement in a different diameter then the others. The transfer case couldn’t be shifted out of 4WD because of the difference in rotational speed of the wheels.
DaimlerChrysler has seen a similar problem in its all-wheel-drive minivans if the tires are not regularly rotated. Their circumferences become different, and the power transfer units fail from the heat generated by different wheel speeds. A difference in circumference of as little as one-half of 1 percent reportedly is enough to ruin a power transfer unit. Chrysler calls for tire rotation every 7,500 miles.
Maybe your vehicle won’t suffer such a fate if you don’t rotate your tires regularly, but there are benefits such as more balanced handling and better traction if you do.
For most vehicles, 7,500 miles is a good time to rotate the tires. It coincides with the annual oil change under “normal” conditions or just about every other oil change under the severe heading.
Rotating your tires while your car is on the lift for an oil change makes the most of your pit stop.
On front-wheel-drive cars, the front tires tend to wear faster than those on the back. That is understandable when you consider that the front wheels not only drive the vehicle, they also steer it, do about 80 percent of the braking and support more weight than the rears.
Consider, also, that each tire encounters different wear patterns and rates at each corner. Without rotating them, you could end up with a tire that is worn out in only one area, but may have plenty of tread otherwise. Wouldn’t it be a shame to trash it?
Tire rotation allows each tire to wear evenly compared to the others.
Replacing all the tires at once maintains the car’s balance and handling performance. Sure, replacing two tires is cheaper than replacing four, but the other two eventually will wear out, requiring a time-wasting trip back to the tire store. Besides, you may find a sale one time but not the next.
Another thing to consider is that tiremakers are constantly improving their tires, so the pair you buy today may not match those you buy in a few months.
If one or more of your tires is wearing differently or more rapidly than the others, get your car’s steering and suspension checked. If problems are left uncorrected, you new tires may wear out too soon. No amount of rotation can compensate for failing parts.
What is the proper rotation pattern? Consult your owner’s manual, but the Tire Industry Safety Council offers some general guidelines. Consult and follow the manufacturer’s recommendations in the owners’ manual for specific tire rotation procedures:
On front-wheel-drive cars, move the two front tires directly to the back on the same side; crisscross the rear tires to the front.
On rear-wheel-drive cars, crisscross the front tires to the rear and move the rear tires directly to the front on the same side.
On all-wheel-drive vehicles, crisscross the fronts and rears in an X-pattern.
On vehicles with unidirectional tires (those that must rotate in a clockwise and counterclockwise direction, depending on which side of the vehicle on which they are installed), move the tires front-to-back and back-to-front only.
On cars in which the front tires are a different size than the rears (but not directional), swap them from left to right across the same axle.
Tires’ turn in the rotation
The goal of tire rotation is to ensure even wear for all four tires. Different types of vehicles and tires require different procedures. Here are some general guidelines. Consult your owner’s manual for procedures specific to your vehicle:
Rear-wheel-drive
Crisscross the front tires to the rear and move the rear tires directly to the front on the same side.
Why: Most of the torque applied to a rear wheel is by driving though there is some braking torque. The wear pattern of the tire is affected by the torque application. So when you take a tire directly to the front, it does not change rotation, but the torque shifts because there is only braking torque on the front wheel. Crisscrossing a tire from say the driver’s side front to passenger side rear, the torque shifts from driving to braking, and the tire is flipped over, changing the rotation. This helps even out wear across the tire.
Front-wheel-drive
Move the two front tires directly to the back on the same side; crisscross the rear tires to the front.
Why: The front tires perform all of the steering and most of the braking and bear most of the vehicle’s weight. So they are likely to wear out faster than the rear tires.
Front and rear tires differ in size
Swap them from left to right across the same axle.
Why: The difference in size dictates whether the tire can run at the front or rear of the car.
Unidirectional tires
Move the tires front-to-back and back-to-front only.
Why: Unidirectional tires are designed with a tread pattern that is specific to the left or the right side of the car.
All-wheel-drive
Crisscross the fronts and rears in an X-pattern.
Why: The reasons are similar to those for RWD. Though in a AWD vehicle every wheel is a drive wheel, the driving is done primarily with the rear wheels in most cases. So most of the torque applied to a rear wheel is driving torque. Crisscossing tires on an AWD vehicle helps even out wear for the same reasons as on a RWD vehicle. Some tire manufacturers advise crossing the fronts and rears (driver side front with passenger side rear) while others advise moving a front tire to the rear like a RWD rotation pattern.
Nuts and bolts of pulsating pedal
A pulsating brake pedal is very annoying. The cause is often warped brake rotors (discs), which are usually damaged by improper lug-nut torque. If all of the lugs are not torqued (tightened) the same or if they were torqued in the wrong sequence, rotor damage is very likely.
If your mechanic uses a pneumatic-impact wrench (the kind that makes a whooping and hammering sound), make sure he also uses a torque stick between the wrench and your wheels. Torque sticks limit the amount of torque applied. They are color-coded to fit all types of cars and trucks.
If your mechanic does not have torque sticks, insist that he use a manual torque wrench to install your wheels.
— Bob Weber.
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Bob Weber is an ASE-certified Master Automobile Technician, having recertified every five years since 1978. Contact him at MMTribune@netscape.net.
