Driver-related causes:
* Excessive braking: Applying too much brake pressure, especially in low-traction situations (wet, icy, or loose surfaces), is the most common cause. The rear brakes lock up more easily than the fronts because the weight transfer shifts forward during braking, reducing the load on the rear tires.
* Sudden braking: Abrupt braking, especially at higher speeds or on uneven surfaces, can overwhelm the tires' grip before the ABS (if equipped) can intervene.
* Poor braking technique: Incorrect braking techniques, like jamming the brake pedal, can easily lead to lockup.
* Over-steering: Turning the steering wheel sharply while braking heavily can upset the balance of the car and cause the rear wheels to lose traction and lock up.
Vehicle-related causes:
* Brake system issues:
* Faulty rear brakes: Worn brake pads, calipers, or other components in the rear braking system can cause uneven braking force, leading to lockup.
* Low brake fluid: Insufficient brake fluid reduces braking effectiveness and can cause a particular wheel to lock up under pressure.
* ABS malfunction: A faulty Anti-lock Braking System (ABS) won't prevent wheel lockup. The warning light will usually illuminate if this is the case.
* Parking brake engaged (partially or fully): A partially or fully engaged parking brake will definitely cause the rear wheels to lock up.
* Tire issues:
* Low tire pressure: Under-inflated tires have less contact patch with the road, making them more prone to locking up under braking.
* Worn tires: Worn tires lack grip, increasing the likelihood of lockup, especially in adverse conditions.
* Uneven tire wear: If one rear tire is significantly worn compared to the other, it may lock up sooner.
* Suspension issues: Problems with the rear suspension can alter the weight distribution and tire contact patch, making the rear wheels more susceptible to lockup.
* Road conditions: Slippery surfaces like ice, snow, oil, or gravel significantly reduce tire grip, increasing the chance of rear wheel lockup.
It's crucial to address any suspected vehicle-related issue immediately. A professional mechanic should diagnose and repair any brake system, suspension, or tire problems.
