Bike Tire Pressure Calculator

How it is calculated

This tool uses a simple empirical rule for a 15 % tire drop: psi = 35.7 × weight ÷ width. Weight is the total system weight in kg, meaning rider plus bike plus anything carried, and width is the tire width in mm. The answer is one pressure in psi, shown to two decimals, and it is not split into front and rear. Because both weight and width appear as a straight ratio, doubling the load doubles the pressure and doubling the tire width halves it. System weight must be 20–300 kg and tire width 15–200 mm; values outside those ranges give no result. There is no input for road surface, tubeless set-up or weight distribution, so judge the result against the maximum pressure printed on the tire.

Common mistakes

• Entering rider weight only. The field is total system weight, so leave out the bike and the figure comes out too low by about a tenth.
• Typing tire width in inches. A 2.3 inch mountain-bike tire must be typed in mm (about 58, which gives 51.70 psi for the 84 kg system); typing 2.3 is below the 15 mm minimum and returns no result.
• Expecting a front and a rear figure. The tool returns one number for both wheels, so you must adjust the rear up and the front down yourself if you want a split.
• Using the result as a hard limit. It has no surface or tubeless correction, so on rough ground or with tubeless tires it is only a starting point to be lowered.
• Ignoring the sidewall maximum. The formula is a straight ratio, and for narrow tires or heavy riders it can exceed what the tire and rim are rated for.