Max and Min Pressure Markings on a Tire

The pressure on the sidewall is a limit, not a target. Think of it as the tire maker saying, "this is as much air as this tire is built to hold." What pressure you actually use is a separate question.

What's printed

Most tires carry a "maximum" pressure, or a recommended pressure range, marked on the side of the tire.¹ The maximum is usually stamped on the sidewall.²

A range gives you a low end and a high end. A single maximum gives you only the ceiling.

Bar and psi

Two units show up. Bar is the unit generally used for tires, and psi (pounds per square inch) is generally used in English-speaking countries.³

Check which unit your pump's gauge uses before you read a number off it. The two units use very different numbers, so mixing them up would leave a tire far too soft or far too hard.

Why the number is a ceiling

Michelin's glossary gives one example. For a Tubeless Ready tire to run with no inner tube, it lists four conditions. The wheel must be a tubeless one. The maximum pressure must not be exceeded. Sealant must be added. The pressure must be checked before each ride.³

So never read the maximum as "the right amount." It's the top of the range the tire is meant to see.

What pressure changes

Pressure shifts how the tire behaves. Lower pressure tends to give more traction and a more comfortable ride.² Too low and the tire has more rolling resistance, and an underinflated tire will be prone to pinch flats.¹

Too high has its own cost. An overinflated tire will give a harsh ride on anything but the smoothest pavement.¹

Width plays in too. Wider tires can run at lower pressures.⁴ Sheldon Brown's article puts the same idea simply: wider tires call for lower pressures, narrower tires for higher ones.¹

One more clue is how the tire sits. A tire is supposed to deflect a bit under load.¹

Where your bike maker's advice lives

The sidewall tells you about the tire. It doesn't know your bike, your rim or your weight. The bike's owner's manual is where the bike maker lists tire advice for that model. Some makers also list it on a support page for the model.

If the manual's number and the sidewall disagree, ask the bike maker or the tire maker which to follow. If you can't find a figure, ask the bike maker or the tire maker. This page doesn't give a number for your bike, because no general number would be right.

The other markings near the pressure line are sorted out in the sidewall reading guide.