What pressure should a tire have?
Each type and size of tire has a different pressure range. The range is written or embossed right on the side of the tire.

The actual pressure you choose is dependent on what you are using the bike for, the road surface you ride on and your general preference. A safe choice the middle of the specified pressure range.

Lower pressure will give a bit more comfort, higher pressure gives slightly less rolling resistance. Beware that too low pressure can make the inner tube susceptible to punctures caused by hitting a bump hard (known as 'pinch flats').