Rear Wear on FWD Sedans – Camber, Toe & Aging Subframes

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Front-wheel-drive sedans do most of their work on the front axle, so rear tire wear is easy to ignore until the tires are bald on the inside edge or sawtoothed across the tread. The rear axle on a typical FWD car has no steering and no drive torque, which means its wear patterns are almost always caused by alignment angles that have drifted over time rather than by driving style. A car can still track straight while the rear toe or camber is far out of specification, because the steering wheel does not feel the rear axle at all. That is why rear wear on a Camry, Accord or Malibu often goes unnoticed until a tire inspection catches it.

Signs that the rear axle is wearing the tires

The inside edge of both rear tires is smooth while the outside edge still has deep tread.
A sawtooth pattern develops across the rear tread blocks, sharp on one side and rounded on the other.
The rear tires wear noticeably faster than the fronts even though the fronts do the driving and braking.
The car drifts or steps sideways slightly on crowned roads, a symptom of rear toe misalignment.
Uneven wear returns quickly even after a tire rotation, because the rear angles have not been corrected.
The rear of the car feels loose or wiggly through a lane change at highway speed.
A tire shop notes feathering on the rear tires during a routine rotation.
The vehicle was in a rear-end impact at some point and the rear subframe was never measured.

Why the rear angles drift

Rear toe changes when the subframe or the trailing arm mounting points shift after impact or rust.
Rear camber on many FWD sedans is not adjustable, so any change means the suspension parts themselves have bent.
Worn rear trailing arm bushings let the arm move under load and pull the wheel out of alignment.
A sagging rear spring or broken coil shortens the ride height on one side and tilts the camber.
Cross-axle ride height differences from load changes make the rear toe steer the car under acceleration.
Aging subframes on rust-belt cars lose their mounting hole alignment as the metal corrodes around the bolts.

How to check it

Measure the tread depth across the rear tires with a gauge at the inside, center and outside ribs.
Run a hand across the tread blocks in both directions to feel the sharp and smooth edges of a sawtooth.
Check rear ride height side to side with the car on level ground and the fuel tank at the same level.
Inspect the trailing arm bushings for cracks and for movement when the suspension is pried with a bar.
Look at the rear subframe mounting bolts for rust and for witness marks that show the subframe has moved.
Get a four-wheel alignment reading rather than a front-only one, and compare the rear toe to specification.
Safety note: Never crawl under a car supported only by the factory jack, and always set the parking brake and chock the front wheels before measuring ride height or inspecting bushings.

When to replace and what to buy

Replace cracked trailing arm bushings before attempting any rear alignment, or the angles will not hold.
Replace a sagging rear spring in pairs to keep the ride height and camber matched side to side.
If the subframe mount holes are rusted or elongated, replace the subframe or the mounting brackets instead of forcing alignment shims.
Use alignment shims or eccentric bolts where the design allows, but never bend a suspension arm to force a setting.
Buy complete bushing kits rather than single bushings when several rear arms share the same age and mileage.
After any rear suspension work, have the four-wheel alignment performed with the car loaded to normal driving weight.