Typically, it is written on the inside of the door frame of the drivers side of the car, but as an example:
My 2008 Kia Spectra has the following tire sizes: 195/60R15, which indicates not only the tire circumference, but the width of the tire as well. My tire size is 15 inches. The typical tire pressure for this size of tire is 30 psi, for the front and back tires. Sometimes and depending on the size of the tire, the pressure differs from the front to the back, but not in this case, as all 4 tires are the same size.
30 psi is a good guess for your vehicle as well, if the tires are 15's, if they are 14's then open your drivers side door, and look at the main upright frame post between the front and back door to view the tire sizes and psi requirements.
The 2008 Kia Rio has 16 valves.
The 2008 Kia Rio has an inline 4 engine.
The 2008 Kia Rio has a 5-speed manual.
The 2008 Kia Rio is a gas-powered vehicle.
The height of the 2008 Kia Rio is 4 ft. 9.9 in. (57.9 in.).
The 2008 Kia Rio's turning circle is 32.7 ft..
The 2008 Kia Rio is 13 ft. 10.9 in. (166.9 in.) long.
The curb weight of the 2008 Kia Rio is 2365 lbs..
The 2008 Kia Rio runs on regular unleaded.
The 2008 Kia Rio has double overhead cam (DOHC).
The 2008 Kia Rio has 50.0 in. of rear hip room.
The 2008 Kia Rio has 39.6 in. of front head room.