* Brake Caliper Stuck or Partially Seized: This is the most common cause. A caliper piston might be sticking, preventing the brake pad from fully retracting after you release the brake pedal. This constant, slight pressure causes friction and generates significant heat. You might even hear a dragging sound while driving.
* Brake Pad or Rotor Problem: While less likely to cause *extreme* heat on its own, a severely warped rotor or a pad dragging against the rotor could contribute. Usually, you'd see more symptoms like pulsating brakes or noticeable vibration before significant heat build-up.
* Parking Brake Partially Engaged: Double-check that your parking brake is fully released. Even a slight engagement can cause significant heat buildup in the affected wheel.
* Wheel Bearing Issues (Less Likely): Severe wheel bearing failure *can* generate heat, but this usually manifests as other symptoms like noise (growling, humming) and play in the wheel. Heat from a bearing failure is typically more widespread around the hub, not just the rim.
* Dragging Brake Shoe (if drum brakes): If your Blazer has rear drum brakes (less common on 2003 models, but possible depending on trim), a sticking brake shoe would act similarly to a seized caliper.
What to Do:
1. Safety First: Do *not* touch the rim immediately after driving. It will be extremely hot and could cause burns. Let it cool down completely.
2. Visual Inspection: Once cool, carefully inspect the brake caliper, pads, and rotor for any obvious signs of damage or sticking. Look for discoloration (bluing or browning) on the caliper or rotor, which indicates excessive heat.
3. Feel for Sticking: Try gently pushing and pulling on the brake caliper piston. If it moves freely, it's likely okay. If it's stiff or doesn't move easily, you have a problem.
4. Check Parking Brake: Make absolutely sure the parking brake is fully disengaged.
5. Professional Inspection: If you're uncomfortable performing these checks or if you find anything amiss, take your Blazer to a mechanic immediately. Ignoring a hot rim could lead to brake failure and serious safety consequences.
In short, a hot rear rim strongly suggests a braking system problem. Don't delay getting it checked out.
