Kia Optima: Inflation PressuresAll tire pressures (including the spare) should be checked monthly when the tires are cold. “Cold Tires” means the vehicle has not been driven for at least three hours or driven less than one mile (1.2 km). Recommended pressures must be maintained for optimum vehicle handling, and minimum tire wear.

All specifications (sizes and pressures) can be found on a label attached to the front driver side door.
The correct tire pressure is 30 psi (210 kPa). The compact spare should be maintained at 60 psi (420 kPa).
WARNING - Tire Inflation
Over inflation or under inflation can reduce tire life, adversely affect vehicle handling, and lead to sudden tire failure. You could lose control and have a serious accident. Follow all the guidelines about proper tire maintenance.
Tire Care
Tire RotationPrecautions
✽ NOTICE
The transmitter (or smart key) will not work if any of following occurs:
The ignition key is in the ignition switch.
You exceed the operating distance limit (about 30 m [90 feet ...
Inspection
1.
Check for the following items visually.
A.
Cracks or leakage of the canister
B.
Loose connection, distortion, or damage of
...
Inspection
1.
Ignition "OFF"
2.
Disconnect ambient temperature
sensor.
3.
Check the resistance of ambient
temperature sensor between terminals 1 and 2 ...