To decide how to check brake pads without removing wheel, you need to look at the wheels themselves. If your car has alloy wheels with wide spaces between spokes, you can reach the caliper and brake pads without lifting the car. If you have steel wheels, alloy wheels with small spaces between spokes, or wheel covers, you need to lift the car to access the back side of the caliper. Put a popsickle stick or a straw next to the pad. Mark the stick or straw with a marker where it lines up with the outside of the brake pad backing. Measure 5mm to the inside of this mark. This is the thickness of the pad, minus the backing plate.