What should my
tire Pressure Be?
Many newcomers to cycling don't think about inflating their bike tires to the proper pressure. To them, a tire is either flat or not, either bad or good to ride. The reality is much more complex. Just like for an automobile, bicycle tire inflation can have a dramatic effect on efficiency and handling characteristics, and we cyclists can use some of these effects to our benefit. Let's jump in and learn more about tire inflation.
Tire inflation basics
Road bike tires are always inflated to much higher pounds per square inch (PSI) levels than mountain bike tires. That's because -- with a smaller surface area and less need for traction -- higher PSI allows road bike tiresto sit firmly above the ground with a minimum of surface area in contact. The tires don't sag down and create a large surface area, because it's simply not needed. A typical road tire should be inflated to something between 90 and 120 PSI.
Mountain bike tires, on the other hand, tend to run at much lower PSI. This is because thicker mountain tires have more surface area touching the ground at any given PSI, reducing the amount of load per unit of area, but also because with mountain tires you generally want a bit of sag to increase contact with mud, gravel, snow, and other low-traction surfaces. Most mountain bike tires are inflated to between 25 and 40 PSI.
Hitting the PSI sweet spot
Too high of a tire pressure can make your ride feel very bumpy and harsh, but may increase performance on fast turns and boost efficiency a small amount. With mountain bikes, high pressure can also cause a tire to "bounce" off obstacles rather than rolling over them smoothly. On the other hand, lower pressure can make your bike handle sloppily and reduce efficiency -- and also put you in additional danger of pinch flats -- but can improve traction in adverse conditions and generally provides a more comfortable ride.
In general, riders who weigh more will want to use a higher pressure than those who weigh less, and wheels with tubeless tires will use a slightly lower pressure than average. Don't forget, as well, that many riders prefer to use a slightly lower tire pressure on the front tire. This can provide a more comfortable ride without sacrificing performance. Beyond those general guidelines, proper tire pressure is a matter of personal preference.
To get your tire pressure sweet spot, you don't need to look at a bike tire psi chart. Just start by inflating your tire to its maximum pressure (every tire has the maximum tire pressure marked on the side of the tire). Make sure you don't exceed this number! Ride around for a while, then lower your pressure by 10 PSI. Observe the handling characteristics as you ride your normal riding style. Keep adjusting your pressure by five or 10 PSI until you feel like you have found the sweet spot for you, and remember that number for the future.