Tools
Tire Pressure Calculator
Tire pressure is the cheapest adjustment on a bicycle and the one most riders get wrong in both directions. Too low and you get pinch flats and a vague front end. Too high and the tire skitters over anything that is not smooth, which costs grip and comfort without buying any speed. This page gives you a starting number and then expects you to adjust it by feel over a few rides.
The sidewall range is the boundary, and it comes before everything else on this page.Every tire has a minimum and maximum pressure molded into its sidewall. The tire manufacturer set that range for that casing on a rim of the right width, and no calculator anywhere knows more about your tire than they did. If the suggestion below falls outside your printed range, the printed range wins. If your rim manufacturer publishes a lower maximum than the tire, the lower of the two applies.
Work out a starting pressure
Five inputs, no page reload, nothing stored. The formula is printed below the result.
Read it off the sidewall. The first number in a marking like 37-622 is the width in millimeters.
You, dressed, in shoes. Round to the nearest option.
Bags, groceries, a child seat, a rack load.
Where most of the riding happens, not the worst stretch.
Everything here assumes an inner tube rather than a tubeless setup.
Never go outside the range molded into your tire sidewall. That range belongs to your specific tire and it overrides everything below. If the suggestion here falls outside it, use the sidewall figure.
Suggested starting point
Front wheel
56 – 63psi
3.8 – 4.3 bar
Rear wheel
66 – 74psi
4.5 – 5.1 bar
- System weight used
- 175 lb
- Tire width used
- 32 mm
Typically fitted to: Commuters, light touring, cyclocross.
Set the rear first, ride it, and adjust in small steps. A change of a few psi is noticeable; a change of one is not.
Nothing hidden
The formula, printed
This is the entire model. You can work it out on paper and get the same answer the calculator gives, which is the point of printing it.
system weight = rider weight including clothing and shoes + everything carried on the bike front load = 0.47 x rider weight + 0.25 x carried weight rear load = 0.53 x rider weight + 0.75 x carried weight center psi = 79.4 x load / (tire width in mm ^ 1.35), then x surface factor x tube factor surface factor: smooth pavement 1.03, broken pavement or light gravel 1.00, rough gravel or trail 0.93 tube factor: standard butyl tube 1.00, self-sealing tube 1.02 center psi is held between 8 and 120 before the range is worked out printed range = center psi -6% to +6%, and bar = psi / 14.5038
The calibration point is a 25 mm tire under a 165 lb rider with nothing carried, which lands near 90 psi at the rear. The exponent is what makes a wider tire ask for less pressure under the same load.
What this calculator does not account for
- The weight of the bike itself. The model is built around rider weight plus what is carried, and a heavy bike is one reason to sit toward the upper half of the printed range.
- Rim internal width. A tire measures wider on a wide rim than a narrow one, which changes its real volume. Measure the tire as fitted rather than trusting the number on the label.
- Whether the tire is tubeless. Everything here assumes an inner tube, and tubeless setups are usually run lower than a tubed tire of the same size.
- Casing construction and thread count. A supple, high thread count casing behaves differently under load than a thick touring casing of the same width.
- Riding position and frame geometry. A deep road position moves more weight forward than an upright commuter position does.
- Temperature. Pressure drops as it gets colder and rises in the sun, which is a reason to set pressure in the conditions you are about to ride in.
- Suspension. A bike with a suspension fork carries and absorbs load differently from a rigid one.
Reference
Rear wheel starting pressures by width and rider weight
Broken pavement, a standard butyl tube, and nothing carried on the bike. Front wheel figures run roughly ten percent below these. Every one of them is still subject to the range on your sidewall.
| Tire width | 130 lb rider | 165 lb rider | 200 lb rider | 235 lb rider |
|---|---|---|---|---|
| 23 mmOlder road bikes and track-derived builds | 74.6–84.1 | 94.7–106.8 | 112.8–127.2 | 112.8–127.2 |
| 25 mmRoad bikes, the most common modern road width | 66.7–75.2 | 84.6–95.4 | 102.6–115.7 | 112.8–127.2 |
| 28 mmEndurance road bikes and fast commuters | 57.2–64.5 | 72.6–81.9 | 88–99.3 | 103.4–116.6 |
| 32 mmCommuters, light touring, cyclocross | 47.8–53.9 | 60.6–68.4 | 73.5–82.9 | 86.4–97.4 |
| 35 mmHybrids and city bikes | 42.3–47.7 | 53.7–60.6 | 65.1–73.4 | 76.5–86.3 |
| 38 mmGravel bikes and loaded commuters | 37.9–42.7 | 48.1–54.2 | 58.3–65.7 | 68.5–77.2 |
| 42 mmGravel bikes and many e-bike city tires | 33.1–37.3 | 42–47.4 | 50.9–57.4 | 59.8–67.5 |
| 47 mmWide gravel, trekking and cargo bikes | 28.4–32.1 | 36.1–40.7 | 43.7–49.3 | 51.4–58 |
| 50 mm (2.0 in)Cross-country mountain bikes, many e-bikes | 26.2–29.5 | 33.2–37.4 | 40.2–45.4 | 47.3–53.3 |
| 57 mm (2.25 in)Trail mountain bikes | 21.9–24.7 | 27.8–31.4 | 33.7–38 | 39.6–44.7 |
| 61 mm (2.4 in)Trail and enduro mountain bikes | 20–22.6 | 25.4–28.6 | 30.8–34.7 | 36.1–40.8 |
| 66 mm (2.6 in)Plus-size mountain bikes | 18–20.3 | 22.8–25.7 | 27.7–31.2 | 32.5–36.7 |
| 76 mm (3.0 in)Plus and light fat-tire bikes | 14.9–16.8 | 18.9–21.3 | 22.9–25.8 | 26.9–30.3 |
| 102 mm (4.0 in)Fat-tire bikes and fat-tire e-bikes | 10–11.3 | 12.7–14.3 | 15.4–17.3 | 18.1–20.4 |
Where the data runs out
- There is no single published pressure figure for a tire size. Pressure belongs to a specific tire on a specific rim under a specific load, which is why manufacturers print a range on the sidewall rather than a number.
- This site does not hold manufacturer pressure data for individual tire models, and it does not attempt to derive one size from another. If your tire is not in the table below, read its sidewall.
- Some tires state their range in bar only, some in psi only, and some in both. Where only one unit is printed, convert it rather than looking for a second source.
- A few rims, particularly older or lightweight ones, publish a maximum pressure lower than the tires commonly fitted to them. Where the rim maximum and the tire maximum disagree, the lower figure is the one that applies.
- Tubeless setups, inserts and sealant volumes are outside what this page covers. The numbers here assume an inner tube.
Tire pressure questions
More of a rider weight sits over the rear wheel than the front, so the rear tire carries a larger share of the load and wants more pressure to support it. The calculator uses a 47 to 53 split for rider weight and puts three quarters of any carried load over the rear, because that is where racks and panniers sit.
Below the printed minimum the tire can roll on the rim, unseat, or pinch the tube against the rim on an impact. Above the printed maximum you are loading the tire bead and the rim beyond what either was designed for. The range exists because both ends have a failure mode, and no calculator has information about your specific tire that the manufacturer did not have.
Tires leak continuously through the tube and around the valve, and a narrow high-pressure tire loses a larger share of its air in the same time than a wide one does. A weekly check with a gauge suits most riders, with a squeeze test before every ride to catch anything sudden.
Only through weight. The bike and its battery add mass to the system, and heavier systems want more pressure for the same tire. The sidewall range does not change, and the ceiling it sets does not move because the bike has a motor.
Gas pressure falls as temperature falls, so a tire set on a mild afternoon reads lower on a freezing morning without anything having leaked. Set pressure in the conditions you are about to ride in rather than correcting for it in your head.
For everyday riding, yes. Floor pump gauges are generally good enough to get you inside a sensible range and to keep you consistent week to week, which is what matters most. A separate stick gauge is more accurate if you want to compare pressures precisely.