Recumbent Tyre Pressure Calculator

Tuned for recumbents, mixed wheel sizes (700c, 650c, 559, 451, 406, 349), TPU/latex/tubeless setups, and manufacturer min/max limits. Inspired by the SRAM AXS and Vittoria calculators.

Recommended pressures

Front

—psi

— bar

Rear

—psi

— bar

Rider & Bike

Rider weight

Bike weight (incl. usual gear) Same unit as rider weight.

Cargo / panniers (optional)

Weight distribution (front / rear)

Front Wheel

Wheel size (ETRTO)

Tyre width (mm, nominal)

Inner rim width (mm) Wider rims widen the tyre — lowers optimum pressure.

Min pressure (sidewall)

e.g. Schwalbe One: 85 psi.

Max pressure (sidewall)

Rear Wheel

Wheel size (ETRTO)

Tyre width (mm, nominal)

Inner rim width (mm) Typical modern road: 19–21 mm; gravel: 23–25 mm.

Min pressure (sidewall)

Max pressure (sidewall)

How does this calculator work?

The base pressure follows the Berto / Bicycle Quarterly “15 % tyre drop” rule:

P_psi ≈ 2.0 × Load_kg × (25 / width_mm)^1.5

Width here is the effective width on your rim, not the nominal label. The ETRTO/Schwalbe rule is roughly effective = nominal + 0.4 × (rim_inner − 19 mm), so a 28 mm tyre on a 23 mm rim measures ~29.6 mm, which lowers the optimum pressure.

That base is multiplied by:

Wheel size factor — smaller wheels (451, 406, 349) need slightly higher pressure to keep the same percentage drop, because the contact patch geometry changes.
Tube / casing factor — tubeless and TPU lose less energy at lower pressure, so they're run a bit softer (TPU −4 %, latex −3 %, tubeless −8 %).
Surface factor — rougher roads roll faster at lower pressures (down to −15 % on gravel).
Style factor — comfort −7 %, performance +5 %.
Weather factor — wet −7 %, cold −3 %, wet & cold −10 %, hot −2 % (since pressure rises as the tyre heats up).

Recumbents put more weight on the rear wheel than uprights — typically 60–70 %. The presets cover common short-, mid-, and long-wheelbase layouts, plus a custom value.

The result is finally clamped to the sidewall min / max you enter (e.g. Schwalbe One min 85 psi). If the calculated value is outside the safe range, you'll see a warning.