Unit converter
Type in any box; the other two update. 1 bar = 14.504 psi = 100 kPa.
Temperature correction
Tire pressure follows the gas law: as air cools it contracts and pressure drops. Set your pressure at one temperature and see what it reads at another.
degrees, see unit toggle
Pressure now reads approximately
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Why cold pressure changes with the weather
The pressure your gauge reads is the gas pressure inside a fixed volume, and by the ideal gas law that pressure is proportional to absolute temperature. As a practical rule of thumb, tire pressure changes about 1 psi (roughly 0.07 bar) for every 10°F (5.5°C) of air temperature change. Set your tires to 35 psi in a 70°F garage and drive out on a 30°F morning, and they will read about 31 psi — enough to trigger a TPMS warning and enough to measurably hurt handling and wear.
Practical takeaways
- Always set pressure cold — before driving, or at least three hours after. A warm tire reads 3–6 psi high and will leave you underinflated once it cools.
- Check monthly and every big cold snap. The first hard frost of the year is the classic TPMS trigger.
- Follow the door placard, not the sidewall. The sidewall number is the tire's maximum, not your vehicle's recommendation.
- Altitude matters too: gaining 1,000 m raises indicated pressure slightly because atmospheric pressure falls. It is minor next to temperature.
Quick reference: common pressures
| Vehicle / use | Typical cold pressure | bar | kPa |
|---|---|---|---|
| Compact car | 32–35 psi | 2.2–2.4 | 220–240 |
| Mid-size sedan | 33–36 psi | 2.3–2.5 | 230–250 |
| SUV / light truck | 35–41 psi | 2.4–2.8 | 240–280 |
| Loaded pickup (rear) | 50–65 psi | 3.4–4.5 | 340–450 |
| Road bike, 25 mm | 75–85 psi | 5.2–5.9 | 520–590 |
| Gravel bike, 40 mm | 35–45 psi | 2.4–3.1 | 240–310 |
| Mountain bike, 2.4" | 18–26 psi | 1.2–1.8 | 120–180 |
| ATV | 4–8 psi | 0.3–0.6 | 28–55 |
Note: The temperature model assumes a sealed tire and ignores the small volume change of the casing, so treat it as accurate to about ±0.5 psi. Retailer links elsewhere on the site may be affiliate links — see our disclosure.