Tire pressure is the cheapest performance change available on a bike, and the one most riders get wrong. There is nothing to buy. It is a number, a pump, and two minutes. Get it right and you gain rolling speed, grip, and comfort at the same time.
The pressure molded into your sidewall is a safety limit set by the manufacturer, not a recommendation. Your optimal pressure depends on your weight, your measured tire width, the surface you ride on, and how fast you ride it. That is four variables a rule of thumb cannot hold, and a calculator can.
Harder rolls faster, until it does not. Past the point SILCA calls breakpoint pressure, the energy lost to you and the bike vibrating over the road outweighs anything gained from a smaller contact patch. Above it, more pressure makes you slower.
SILCA's road testing puts the cost of running 10 psi below the breakpoint at roughly 1 watt, against about 9 watts for running 10 psi above it. If you are estimating, estimate low. Most riders estimate high.
Two riders 30 kg apart on identical tires have meaningfully different optimal pressures, and so does the same rider on fresh asphalt and on chipseal. A single number printed on a sidewall cannot express that.
SILCA's calculator is the most rigorous public tool for this. It is built on rolling resistance data collected on real road surfaces using the Chung method, not on a steel drum in a lab. We link to it rather than build our own, because there is no sense duplicating the tool that is already the reference.
One caveat worth repeating from SILCA: the calculator does not know your rim and tire limits. Hookless and tubeless setups have hard maximum pressures. Where the manufacturer's figure is lower than the calculator's, the manufacturer wins.
Where the breakpoint comes from, what the testing actually measured, and the one thing a pressure calculator can never tell you about your tires.
A calculator sets your pressure for today's ride. Componentry tracks what every ride does to your tires, chain, cassette, and brake pads, and tells you what needs replacing before it fails on you.
Start your 2-month free trial. No credit card required.