Bike Tire Pressure Calculator
Find a good starting tire pressure for your road, gravel, hybrid or mountain bike. Enter rider and bike weight, tire width, surface and setup to get separate front and rear pressures in PSI, bar and kPa.
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e.g. 700×28c = 28 mm; 2.4 in MTB = 61 mm
How to use the Bike Tire Pressure Calculator
- Enter rider and bike weight in kg or lb (include bags and gear).
- Enter your tire width, ideally measured on your rim, in mm or inches.
- Choose the surface you ride most and your weight distribution.
- Tick tubeless if you run tubeless, and choose your rim type.
- Pump to the front and rear values, then fine-tune a few psi for comfort and grip.
How the pressure is estimated
A tire needs enough pressure to carry its share of the load without deflecting too much. The calculator splits the system weight (rider + bike + gear) between the wheels, then uses a load-and-width model:
base (psi) = 0.842 × average wheel load (lb) ÷ (tire width ÷ 25 mm)1.5 × surface factor × tubeless factor
The rear tire then gets more and the front less, depending on your weight distribution: with a 40/60 split the rear is 5% above the base and the front 5% below. A purely load-proportional split (as in older charts) gives a front pressure that most riders find too low, so the split is softened.
The constant and exponent were chosen so results land in the range of widely used tire-drop charts and modern manufacturer guides for road, gravel and mountain bike tires. It is an engineering estimate, not an official standard, so treat it as a starting point.
Typical starting pressures (75 kg rider + 10 kg bike, average surface)
| Tire | Front | Rear |
|---|---|---|
| Road 25 mm | 75 psi (5.2 bar) | 83 psi (5.7 bar) |
| Road 28 mm | 63 psi (4.4 bar) | 70 psi (4.8 bar) |
| Road / gravel 32 mm | 52 psi (3.6 bar) | 57 psi (3.9 bar) |
| Gravel 40 mm | 37 psi (2.6 bar) | 41 psi (2.8 bar) |
| MTB 2.4 in (61 mm) | 20 psi (1.4 bar) | 22 psi (1.5 bar) |
Tube-type tires, 40/60 weight distribution. Tubeless setups, rough surfaces and trails call for lower values; use the calculator for your exact numbers.
Tips for setting tire pressure
- Check pressure before every ride on road bikes; tires lose a few psi per day.
- Use a floor pump or digital gauge you trust; gauges can differ by 5 psi or more.
- Lower pressure is often faster on rough roads because the tire absorbs bumps instead of bouncing the bike.
- In the wet, drop 5–10% for more grip.
- Never go below the minimum or above the maximum printed on the tire sidewall.
Frequently asked questions
What tire pressure should I run on my road bike?
It depends mostly on weight and tire width. For a 75 kg rider on a 9 kg bike with 28 mm tires on average roads, about 62 psi front and 69 psi rear is a good start; with 25 mm tires it is closer to 74 and 82 psi.
Why is the rear tire pressure higher than the front?
Most bikes carry about 55 to 60% of the weight on the rear wheel, so the rear tire needs more support. A typical split is about 5 to 15% more pressure in the rear than the front.
Do wider tires need less pressure?
Yes. A wider tire has more air volume and a larger contact patch for the same deflection, so it can support the same load at lower pressure. Going from 25 mm to 32 mm lowers the pressure needed by roughly 30%.
How much lower can I run tubeless tires?
Tubeless tires cannot pinch flat because there is no tube, so riders often run them about 5 to 10% lower for more grip and comfort. This calculator lowers pressure by 7% for tubeless.
What is the maximum pressure for hookless rims?
The ETRTO and ISO standards limit hookless road rims to 5 bar (72.5 psi). Always respect the lower of the rim maker's and the tire maker's maximum pressure.
How do I convert PSI to bar?
Multiply PSI by 0.0689 to get bar, or multiply bar by 14.5 to get PSI. For example, 80 psi is about 5.5 bar.
How accurate is this tire pressure calculator?
It gives a starting point based on wheel load and tire width, similar in spirit to the 15% tire-drop method. Casing stiffness, rim width, rider style and conditions all matter, so adjust a few psi up or down by feel and never exceed the tire's printed limits.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.