Front tyre
– psi
Rear tyre
– psi
Always check the sidewall
Never go above the maximum (or below the minimum) pressure printed on the tyre sidewall, whatever any calculator says. If this tool suggests more than the sidewall maximum, use the sidewall figure.
How it works
It splits your total weight between the wheels (more on the rear, because that's how bikes balance), then finds the pressure that gives each tyre about 15% "sag". Wider tyres hold you up with far less pressure — a 57 mm MTB tyre runs around 20 psi while a 25 mm road tyre needs 80+.
- Rougher surfaces → lower pressure, for grip and comfort.
- Tubeless → about 10% lower, since there's no tube to pinch.
- Front a touch softer than rear is normal and good.
Fine-tuning by feel
Treat the result as a starting point. If the ride feels harsh and skittery, let out 5 psi. If the tyre squirms in corners or you hit the rim on bumps, add 5 psi.