Fiat Abarth 500 2015 Owner's Manual page 284

282 STARTING AND OPERATING
The tire pressure will vary with temperature by about 1
psi (7 kPa) for every 12°F (6.5°C). This means that when
the outside temperature decreases, the tire pressure will
decrease. Tire pressure should always be set based on
cold inflation tire pressure. This is defined as the tire
pressure after the vehicle has not been driven for at least
three hours, or driven less than 1 mile (1.6 km) after a
three hour period. The cold tire inflation pressure must
not exceed the maximum inflation pressure molded into
the tire sidewall. Refer to "Tires – General Information"
in "Starting And Operating" for information on how to
properly inflate the vehicle's tires. The tire pressure will
also increase as the vehicle is driven, this is normal and
there should be no adjustment for this increased pres-
sure.
The TPMS will warn the driver of a low tire pressure if
the tire pressure falls below the low pressure warning
limit for any reason, including low temperature effects, or
natural pressure loss through the tire.
The TPMS will continue to warn the driver of low tire
pressure as long as the condition exists, and will not turn
off until the tire pressure is at or above the recommended
cold tire pressure on the placard. Once the low tire
pressure warning (Tire Pressure Monitoring Telltale
Light) illuminates, you must increase the tire pressure to
the recommended cold tire pressure in order for the Tire
Pressure Monitoring Telltale Light to turn off. The system
will automatically update and the Tire Pressure Monitor-
ing Telltale Light will turn off once the system receives
the updated tire pressures. The vehicle may need to be
driven for up to 20 minutes above 15 mph (24 km/h) in
order for the TPMS to receive this information.
For example, your vehicle may have a recommended
cold (parked for more than three hours) tire pressure of
30 psi (207 kPa). If the ambient temperature is 68°F (20°C)
and the measured tire pressure is 27 psi (186 kPa), a
temperature drop to 20°F (-7°C) will decrease the tire
pressure to approximately 23 psi (159 kPa). This tire