Why different front and rear pressures?

Most riders carry roughly 55% of their weight on the rear wheel and 45% on the front. Because each wheel is inflated to the load it actually carries (Frank Berto’s 15% tyre-drop method), the rear typically runs around 15–20% higher pressure than the front — for example 90 psi rear / 73 psi front for an 83 kg rider+bike on 25 mm tyres. Run the front a little softer for grip and comfort.

Is higher pressure always faster?

No. Research shows that on real roads, lower pressures can be faster because the tyre absorbs bumps instead of bouncing. The old "hard tyres are fast" advice is outdated — the Berto 15% tyre-drop target this tool uses aims for that comfort/speed sweet spot.

How does tyre width affect pressure?

Wider tyres support the same load at lower pressure. As a rough guide, a 28 mm tyre at around 75 psi gives a similar contact patch and ride to a 25 mm at around 90 psi, but with more comfort and grip. This calculator recomputes the exact figure from the Berto 15% tyre-drop formula for your chosen width.

Should I use tubeless?

Tubeless allows running 5-10 psi lower than clincher for the same performance, improving comfort and grip. It also reduces puncture risk.

Tyre Pressure Calculator — Optimal PSI for Your Setup

How We Calculate This

Pressure Calculation

The calculator applies Frank Berto’s 15% tyre-drop method (Bicycle Quarterly, "All About Tire Inflation"). It splits your total system weight onto the front and rear wheels using your weight distribution, then inflates each wheel to the pressure that produces a ~15% tyre drop for the load it carries: P (psi) = 600 × load(lb) ÷ width(mm)² + 0.75 × width(mm) − 25.

Because each wheel is solved independently, the rear runs higher than the front — typically around 15–20% more for a 45/55 split. Wider tyres need lower pressures for the same load. Gravel, rough or wet surfaces drop the figure further so the tyre can absorb bumps rather than bounce, which is both faster and more comfortable on real roads.

Tubeless setups are reduced by 5 psi, and the result is capped within sensible sidewall limits for the tyre width.

Frequently Asked Questions

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Last updated: 2025-02-20

All calculations are estimates. Always verify results and consult a professional bike fitter where appropriate.