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Tire Pressure Calculator
This free tire pressure calculator finds the recommended tire pressure for your vehicle, adjusts it for the load you are carrying and the temperature outside, and converts the result between PSI, bar, and kPa. Pick your vehicle type, load, and temperature to get separate front and rear pressures.
| Front tires | Rear tires | |
|---|---|---|
| PSI | 32.0 | 32.0 |
| bar | 2.21 | 2.21 |
| kPa | 221 | 221 |
Check pressure when tires are cold — before driving, or after the car has sat for at least 3 hours.
How it works
Tire pressure is measured in PSI — pounds per square inch — and it is simply the force of the air pushing outward against the inside of the tire. Every vehicle maker publishes a recommended cold pressure for its models, tuned to the weight of the vehicle, the size of its tires, and the way it handles. This calculator starts from the typical recommended pressure for your vehicle type, then adjusts it for the load you are carrying and the temperature outside.
The starting pressures are the common placard values for each type. A sedan or hatchback usually runs 32 PSI at the front and 32 PSI at the rear. An SUV or crossover typically needs 33 PSI in front and 35 PSI in the rear. A pickup truck starts at 35 PSI front and 38 PSI rear, a minivan at 35 PSI front and 36 PSI rear, and a motorcycle at 32 PSI front and 36 PSI rear. These are typical values, not a substitute for your own placard — two sedans from different makers can differ by a few PSI, and the placard always wins.
Load changes the numbers because a tire is a spring made of air: more weight on it means it needs more air pressure to hold its shape. With only the driver aboard, the calculator takes 1 PSI off both axles. A normal load — a few passengers and everyday cargo — needs no change. A heavy load or towing adds 2 PSI to the front and 4 PSI to the rear, because the extra weight sits mostly over the rear axle. That is why many door placards print two sets of numbers, one for light loads and one for a fully loaded vehicle.
Temperature matters because air expands when it warms and contracts when it cools. The rule of thumb used by tire makers is about 1 PSI for every 10°F of change from a reference temperature of 65°F. So if the morning is 35°F, a tire set to 32 PSI at 65°F will read about 29 PSI — it has lost roughly 3 PSI overnight, and the tire pressure warning light often appears on exactly such a morning. The calculator applies that correction and rounds the result to the nearest half PSI, because most gauges are not more precise than that. If you enter the temperature in Celsius, the tool converts it to Fahrenheit first, then applies the same rule.
The result is shown in PSI, bar, and kPa so it works with any gauge or placard. One bar equals 14.5 PSI, and one PSI equals 6.89 kPa, so a typical 32 PSI tire reads about 2.21 bar or 221 kPa. Use whichever unit your gauge shows, but never mix them up: inflating a tire to 32 bar instead of 32 PSI would be dangerously over the limit.
Measure pressure when the tires are cold — before driving, or after the car has sat for at least three hours. Driving warms the tires and raises the reading by roughly 3 to 5 PSI, so a hot reading makes a correctly inflated tire look overinflated. If you must check a warm tire, do not let air out to reach the cold number — note the reading and recheck it once the tires have cooled.
Worked example
A family in Ohio drives an SUV on a cold January morning. The temperature is 35°F, the car carries two adults, two children, and luggage — a normal load.
Step 1: Pick SUV / crossover as the vehicle type. The typical base pressure is 33 PSI front, 35 PSI rear.
Step 2: Pick Normal load, which adds nothing — the adjustment is 0 PSI.
Step 3: Enter 35°F. The temperature adjustment is (35 − 65) ÷ 10 = −3 PSI.
Step 4: Front = 33 + 0 − 3 = 30.0 PSI. Rear = 35 + 0 − 3 = 32.0 PSI.
The tool shows exactly that: front 30.0 PSI (2.07 bar, 207 kPa) and rear 32.0 PSI (2.21 bar, 221 kPa).
A second check: the same SUV, heavy load with a trailer, on a 95°F afternoon. The base is still 33 and 35 PSI, the heavy-load adjustment adds 2 PSI front and 4 PSI rear, and the temperature adjustment is (95 − 65) ÷ 10 = +3 PSI. Front = 33 + 2 + 3 = 38.0 PSI, rear = 35 + 4 + 3 = 42.0 PSI — exactly what the tool shows, and a reminder to recheck the placard, because some vehicles print a separate heavy-load figure.
FAQ
Where do I find the correct tire pressure for my car?
On the placard on the driver's door jamb, on the inside of the fuel filler door, or in the owner's manual. That number is the pressure your vehicle maker recommends for your exact car and its original tire size. The number stamped on the tire sidewall is the maximum pressure the tire can safely hold, not the pressure you should drive on.
How does temperature change tire pressure?
Tire pressure changes by about 1 PSI for every 10 degrees Fahrenheit of temperature change. When the air inside a tire gets colder it contracts, so pressure falls; when it warms up it expands, so pressure rises. A tire set to 32 PSI on a 65-degree day can read about 29 PSI on a 35-degree morning, which is why cold snaps make tire warning lights come on.
Should I check tire pressure when the tires are hot or cold?
Check it cold, before driving or after the car has sat for at least three hours. Driving warms the tires and raises the reading by roughly 3 to 5 PSI. If you must check a warm tire, do not let air out to reach the cold number — recheck it cold later.
Is it bad to drive with low tire pressure?
Yes. Underinflated tires flex more as they roll, which builds heat, wears the outer edges of the tread, and hurts fuel economy. Severe underinflation is a leading cause of blowouts, and a tire just 6 PSI low can noticeably shorten the tire's life.
What is the difference between PSI, bar, and kPa?
They are three units for the same pressure. PSI is pounds per square inch and is standard in the United States. Bar is common in Europe, and kPa is the metric unit on many door placards. 1 bar equals 14.5 PSI and 1 PSI equals 6.89 kPa, so a typical 32 PSI tire reads about 2.2 bar or 221 kPa.