# Tire Pressure Calculator

### The days when we pumped up our tires to the maximum pressure – hoping to optimize performance – are long over.

Today we know that the best tire pressure depends on your tire size, your weight (and that of your bike), and your riding style and preferences. Lower pressures optimize comfort and tire grip. They also result in fewer flat tires: A soft tire often rolls over debris that would puncture a tire inflated to high pressure.

#### Tire Pressure Calculator

Inflate your tires to this pressure:
Soft:
Firm:

The calculator gives you two tire pressure recommendations. Use the ‘Soft’ value for gravel, rough pavement, or if you prefer a more comfortable ride. Use the ‘Firm’ value if you like your bike to have a firm feel. The ‘Firm’ values also provide a considerable margin of safety if your pressure drops a bit. With the ‘Soft’ pressure, you are stressing your tire casing more, and it may wear out faster.

Bicycle Quarterly’s extensive tire tests have shown that – on smooth roads – supple high-performance tires roll at the same speed at either of these two pressures. Pressures between these two values roll a little slower. On rough surfaces, your bike will be faster at the ‘Soft’ pressure.

This pressure calculator is intended only as guidance. Also remember that your pump’s gauge may not be accurate. When in doubt, use a tire pressure that feels right and safe to you instead of the values provided by the calculator.

Do not exceed the maximum pressure for your tire and/or rim. For tubeless installation, many tires have lower maximum pressures than what’s listed on the sidewall. Refer to the tire/rim manufacturers specifications.

### Front v. Rear Pressure

Most bikes carry more weight on the rear wheel than the front. However, when you brake hard, almost the entire weight shifts to the front wheel. For that reason, it’s not advisable to run a lower pressure in the front tire.

### Even lower pressure?

On very rough surfaces, many riders run even lower pressures than the ‘Soft’ values. This increases speed and comfort. It comes with trade-offs: There is less support for the weight of rider and bike. If these low pressures are used on firm, high-grip surfaces, the tire can collapse under hard cornering or braking. The tires also flex more at ultra-low pressures, so the sidewalls can wear out faster.

### Don’t sweat it!

The ‘right’ pressure will make your bike a little faster and more comfortable, but the difference isn’t huge. You won’t get dropped by your friends because you’re running your tires at too high pressures. More important than tire pressure is choosing supple tires that offer both more speed and more comfort than stiff tires.

#### Background

Lower pressure means less vibration and less energy lost to suspension losses. That makes up for the higher hysteretic losses due to greater deformation of the tire.

These two factors – suspension losses and hysteretic losses – do not interact in a linear way, as shown in the conceptual graph on the left. The result: Mid-range pressures actually roll a little slower than either high or low pressures.

Based on Bicycle Quarterly’s tests of rolling resistance for different tire widths and pressures, together with Frank Berto’s measurements of tire drop under different weights, we have established two different tire pressure charts. These charts were translated into this Tire Pressure Calculator.