- A 4-wheel alignment with tire rotation
Wheel Alignment: Sending You Straight Down the Road
Most cars only received alignments on their front two wheels up until 30 years ago. Read on to find out why that changed.
Many mechanics spend their days tinkering with cameras, though they have no portrait portfolio to show for it. That’s because computerized wheel-alignment equipment typically relies on four high-tech camera systems mounted around the wheels. Instead of snapping pictures, each camera maps its own location, noting the angle of its designated wheel and axle in relation to its three counterparts. From these measurements, automotive technicians can determine if and where alignments are needed, be it adjusting a positive camber—when the wheel angles too far out from the center of the vehicle—or fiddling with a negative caster, which occurs when the steering axis pivots to the front of the car. Techs also inspect the wheel’s toe; if the two front tires are closer together than the back tires, this is known as toe-in (imagine a pigeon-toed car), while the opposite is called toe-out (bowlegged). When not angled correctly, the suspension and steering systems can cause a range of problems, from simply wearing down tires to inhibiting the car from driving in a straight line.
Prior to around 1980, the majority of vehicles only received alignment on their front wheels, leaving the back rollers to fend for themselves. Yet, with the influx of four-wheel-drive vehicles came the necessity for all-wheel alignments. Today, 44% of cars receive four-wheel alignments, and though more expensive than their front-end or rear-axle thrust-angle predecessors, the service is a definite necessity for any car with four-wheel drive or an adjustable rear suspension.