If you've been shopping around for an alignment for your car, you've probably heard that you need (or should get) a four-wheel alignment. This procedure might make sense if you drive a 4WD or AWD vehicle, but what about everyone else? As it turns out, most modern front-wheel drive and rear-wheel drive vehicles also require adjusting all four wheels.
Understanding why this is the case requires understanding a few of the basics of modern vehicle suspension and the role that alignments play in keeping your car safely on the road.
Essential Alignment Angles Explained
You might be familiar with three terms that commonly come up when dealing with alignment: caster, camber, and toe. These terms describe the geometry of your vehicle's wheels and tires relative to the vehicle chassis. Manufacturers set these angles from the factory to achieve varying levels of cornering performance, straight-line stability, and steering response.
As you drive your vehicle every day across uneven and imperfect road surfaces, the steering and suspension components that maintain these angles can wear. Unsurprisingly, this wear will cause your wheels to drift out of alignment. While the effects might be subtle at first, misaligned wheels will eventually impact the responsiveness and stability of your car.
Independent Rear Suspensions and Wheel Alignments
Many vehicles used independent front suspensions and live-axle rear suspensions in the past. As the name implies, this design effectively linked the rear wheels together with a solid axle. As a result, one wheel's movement would affect the motion of the opposite wheel. With an independent rear suspension, each wheel can move without directly affecting the other.
However, live-axle suspensions do not require any alignment adjustments. This situation makes sense due to the relative simplicity of the design. On the other hand, an independent rear suspension can become misaligned in the same way as the front wheels. These misalignments can impact your vehicle's performance and cause your tires to wear out more quickly.
Why You (Most Likely) Need a Four-Wheel Alignment
While a handful of modern vehicles still use live rear axles, they're increasingly rare on mainstream cars, SUVs, and crossovers. Independent rear suspensions typically provide better handling, a more comfortable ride, and even better traction, making them the preferred choice for most manufacturers. You'll normally only find live rear axles on trucks or vehicles with serious off-road capabilities.
While it's a common misconception that four-wheel alignments are only necessary for vehicles with 4WD or AWD, the reality is that any vehicle with an independent rear suspension requires them. Since most modern cars use this suspension design, there's a good chance that your vehicle needs a four-wheel alignment regardless of its drive configuration.