One of the most common questions cyclists have is,
- How much air should I put into my bike tires?
- What’s the ideal tire pressure for my bike?
The answer is not as straightforward as it seems.
The ideal tire pressure depends on many factors, such as tire type, width, compound, weight, rim width, riding, and surface conditions.
Here’s a general overview of the tire pressure range for the common type of bike and tire.
| Bike type | Tire type | Tire pressure |
|---|---|---|
| Road bike | Clincher | 80 to 120psi |
| Road bike | Tubeless | 45 to 70psi |
| Road bike | Tubular | 120 to 160psi |
| Mountain bike | Tubeless | 20 to 30psi |
| Mountain bike | Clincher | 30 to 40psi |
| Gravel bike | Tubeless | 30 to 50psi |
| Commuter bikes | Clincher | 70 to 100psi |
Finding the correct tire pressure for you and your bike requires you to understand and appreciate all the different factors that could affect the performance of your tires.
Cyclist’s weight
The total weight (cyclist + bike + cargo) is the most crucial factor when determining the right tire pressure.
The above chart from Frank Berto provides a basic explanation of the ideal tire pressure. Note that it mentions Wheel Load on the x-axis and total weight. That’s because the weight distribution between the front/rear wheel is not 50/50 but more towards 30/70.
There’s more weight loaded on the rear than the front, which is why you’ll also notice your rear tires usually wear out quicker.
The higher the weight, the more the tire will be deformed, thus increasing the rolling resistance. This can be countered by increasing the tire pressure. Hence, a lighter cyclist typically needs a lower tire pressure than a heavier rider.
Running on higher tire pressure for a light cyclist provides little improvement to rolling resistance. This could easily result in an uncomfortable and bumpy ride as the bike experiences more vibration due to the hard tires.
Key takeaway : Lighter riders can run on a lower tire pressure compared to heavier riders, given that all the other factors remain constant.
Tire width
Most 700c road bike tires are sold in either 25 or 28mm widths. Wider tires are gaining serious traction as disc brakes, and tubeless tires are becoming the norm as the quest for wider and more comfortable tires intensifies.
Just 5 to 7 years ago, it’s uncommon to see pro cyclists riding 25mm tires. Many of them are racing on 28mm tires today. In races such as the Paris Roubaix and Tour of Flanders, 30mm is common, while some will run up to 32mm too.
Why is this the case?
The answer lies in a concept called casing tension. If you’re a geek, FLO Cycling has a thorough explanation using mathematical formulas.
Here’s the gist of it.
As the bike tires get wider, the casing thickness remains the same (we talking about the same tire, just different widths).
To maintain the same casing tension for both the 25mm tire and 28mm tire, the 28mm would need to run at a lower pressure.
Lower tire pressure also increases tire grip, especially when riding in wet conditions. Though lower pressure offers enhanced comfort, you should be cautious not to drop the tire pressure too low since it increases the chances of snakebite punctures when the inner tube is trapped between the tire and the wheel rim.
Regardless of the tire width, you’ll also want to be within the recommended (minimum and maximum) tire pressure of the tire and rim.
You can often find these values are usually printed on the tire sidewall and rim. Note that some carbon clincher wheelsets have a maximum pressure lower than the tire’s maximum pressure.
Key takeaway : Wider tires can run at lower pressures.
Tire type
Generally, tubular tires are superior because they are suppler and have lesser rolling resistance. That’s why you see tubular being used in racing, especially by the pros. Sometimes, tubular are referred to as tubs or racing tires.
- Tubular tires can run much higher tire pressure (up to 160psi) due to their one-piece design. The tube is sewn inside the tire, unlike a clincher tire where the tube and tire are separated.
- Clincher tires sit between tubular and tubeless tires. Typical tire pressure for clincher tires is between 80 to 120psi.
- Tubeless tires run the lowest tire pressure among all. Tubeless tire pressure is generally between 45 to 70psi.
These days, tubeless tires are becoming the norm, taking over from clincher tires.
Key takeaway : Tubulars can run higher pressure than tubless and clinchers tires.
Tire compound
The tire compound has a considerable effect on how tires behave upon inflation. Consider going for supple tires to get the most performance out of the tire casing.
Generally, race tires are more supple than training tires.
Supple tires are softer and hence can flex easily. This is countered by using higher pressure. On the contrary, a stiff sidewall will require more energy to flex; hence you can run it on lower pressure.
Numerous rubber compounds and tire casings are currently used in the bike industry. The most talked-about compound is graphene, which is used by Vittoria in their Corsa range.
Key takeaway : Suppler tires can run at a higher pressure.
Internal rim width
The internal rim width affects the shape and size of a clincher and tubeless tire. There is an ideal internal rim width for each tire width, as suggested by the ETRTO standards.
| Tire width (mm) | Internal rim width (mm) range |
|---|---|
| 23 | 13 to 16 |
| 25 | 13 to 17 |
| 28 | 15 to 19 |
| 32 | 15 to 20 |
| 35 | 17 to 22 |
| 40 | 17 to 13 |
| 50 | 17 to 27 |
You’ll often see road bike wheelsets with 15C, 17C, or 19C in their specifications. This indicates the internal rim width.
Have you heard about the light bulb effect?
The light bulb effect happens when you run a wider tire on a narrow rim, such as a 28mm on a 15C wheelset. While wider tires are more comfortable, it’s not recommended with a narrower rim as it’ll drastically affect the bike handling, especially during cornering.
For the aerodynamic geeks, you might want to do the opposite. Consider running a narrower tire on a wider rim, such as a 23mm tire on a 17C rim. Check out the results of a bicycle wheel aerodynamics testing performed by Hambini Performance Engineering.
Key takeaway : Use the right tire width to prevent the formation of a bulb shape.
Riding terrain and road surface
For rough and uneven terrains, a lower tire pressure helps the tire deform easily to absorb vibrations. For paved roads, higher pressure helps reduce the rolling resistance.
One good example is to compare track racing to mountain biking. Both are on completely different ends of the surface spectrum.
- The indoor cycling velodrome’s surface is smooth; hence, track bikes usually run very high tire pressure, between 140 to 220 psi.
- On the other hand, mountain bike tires usually have a low tire pressure of between 20 to 40psi.
- If you’re riding indoors on a turbo trainer using trainer tires, keep in mind that lower pressure = more resistance.
While tire pressure plays a vital role in your ride comfort, don’t discount the type of bike frame you’re riding. A carbon frame is usually less compliant and harsher than steel or titanium.
Key takeaway : Consider lowering the tire pressure if riding on rough and uneven surfaces.
Riding conditions
Wet conditions, often due to rain, could reduce your tire pressure. There’s no magic number of how much psi you should lower.
Most cyclists usually give the Presta valve 2 to 3 short presses to lower the tire pressure. The main reason you want to lower the is to increase traction in wet conditions. A larger tire patch in contact with the surface will give you more grip.
Key takeaway : Slightly lower the tire pressure if you’re riding in the wet to improve grip and traction.