Tyre Pressure Calculator — Optimal PSI for Your Setup

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. Rougher and wetter surfaces drop the figure further so the tyre can absorb bumps rather than bounce, which is both faster and more comfortable on real roads. Those drops are absolute psi offsets rather than percentages, because that is how everyone who publishes one expresses it: rough road and chipseal -4 psi, wet -10 psi, and gravel on a four-step ladder from -3 psi for smooth hardpack to -9 psi for loose and chunky. Gravel is split because it spans a wide range: Silca publish four gravel categories and rank the smoothest as easier going than poor tarmac, so a single gravel figure would be wrong at both ends.

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

Working figures for this are collected in our Tyre Pressure Guide reference table.