Bike Tire Pressure by Weight Calculator
Estimate front and rear tire pressure from your total system weight and tire width for a comfortable, low-rolling-resistance ride.
How it works
Pressure ∝ wheel load ÷ tire width^1.42 · Rear load = weight × rear% · Front load = weight − rear load
Correct tire pressure is set by the load each wheel carries and the tire's air volume, not by the number stamped on the sidewall. Wider tires hold more air, so they need far less pressure to support the same weight — and the rear wheel, carrying more of your body weight, wants more pressure than the front. This estimate uses an empirical width-and-load fit; treat it as a starting point and drop pressure until the ride feels planted without bottoming out.
Worked example
An 85 kg system on 28 mm tires with 55% on the rear: the rear carries ~47 kg and the front ~38 kg. The fit lands near 70 psi rear and 57 psi front on smooth tarmac — reduce a few psi for rough roads.
Frequently asked questions
Why lower pressure than the sidewall maximum?
The sidewall number is a safety maximum, not a recommendation. Running near it on modern wide tires makes the ride harsh and can actually increase rolling resistance on real roads because the tire skips over bumps instead of absorbing them.
Why more pressure in the rear tire?
You sit farther back, so the rear wheel typically carries about 55% of the total weight. Matching pressure to load keeps both tires deforming by a similar amount for balanced grip and comfort.
How should I fine-tune from here?
Start at the estimate, then adjust in 3–5 psi steps: drop pressure if the ride is harsh or you have no grip, add pressure if you feel the rim bottoming on bumps or the tire squirming in corners.
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Estimate only — never exceed your tire and rim maximum pressure ratings.