If your vehicle is showing hissing sound from wheel wells after turning off the car, here are the most likely causes and the parts you'll need to fix each one.
Normal operation of the air conditioning creates condensation. If the A/C drain tube is routed near the exhaust, water dripping onto the hot pipes creates a hissing or sizzling sound audible near the front wheel wells.
A nail in the tread, a damaged sidewall, or a leaking valve stem will release air continuously. This hissing is easiest to hear in a quiet environment right after turning the car off.
On vehicles equipped with air ride, a leak in an air strut, bag, or airline will hiss as the system tries to vent or loses pressure, often causing that corner of the car to sag after parking.
After shutting off the engine, the high and low-pressure sides of the A/C system equalize through the expansion valve. This creates a faint, temporary hissing sound near the firewall and front wheel wells.
A pinhole leak in a coolant hose can spray pressurized coolant onto hot engine components or the exhaust. The resulting steam creates a hissing sound that escapes through the wheel well area.