Bike Tire Pressure Calculator

The pressure stamped on your tire is a maximum, not a target. Most riders run far too high and lose grip and comfort for it. Enter your system weight, tire width, type and surface above, and the calculator hands you a front and rear PSI to start from. The rear always reads higher, because that is where most of your weight sits.

What the calculator does

It runs a simple heuristic. Base pressure drops as tire width goes up, then scales with how much you and your bike weigh. After that it applies a factor for the surface and a discount for tubeless setups, which seal and run lower than tubes. The front and rear split (default 45/55) sends more air to the rear wheel.

This is an approximation, not a lab model. The well-known SILCA pressure model is proprietary and uses tire casing data we cannot see. What you get here is a defendable starting point built from rider weight, width and surface, the three inputs that move pressure most. Treat the output as a baseline to refine by feel, not a precise reading.

How to use the result

Set both tires to the numbers, then ride a familiar stretch. If the bike feels harsh over small bumps, drop 2-3 PSI per wheel and try again. If the tire feels vague in corners or you hear it bottom out on a hard edge, add a few PSI back. Lower pressure rolls better on rough ground up to a point, then loses speed once the tire deforms too much.

Weight is the input people get wrong. Use your full riding weight plus the bike, bottles, and anything in your bags or pockets, not your bodyweight alone. A loaded bikepacking setup can add 10 kg, and that air has to go somewhere.

Road, gravel and mixed

A 28 mm road tire and a 40 mm gravel tire live in different worlds. The wider tire holds more air volume, so it needs far less pressure to support the same load. That is why your gravel numbers come back so much lower than your road ones. Both are correct for their job.

For mixed surfaces, where smooth tarmac turns to dirt mid-ride, the calculator splits the difference. Lean toward the lower end if the rough sections dominate, the higher end if most of the ride is paved.

Once you have your pressure dialed, two more tools help you ride faster for the same effort. The bike power and speed calculator shows how watts translate to pace, and the gear ratio calculator helps you pick a setup that keeps your cadence where you want it.