Tire Pressure Calculator
There is no single correct tire pressure. The right number balances your weight on each wheel, your measured tire width, the surface, and your casing. This calculator uses the Berto 15% tire-drop model to set front and rear pressure that rolls fast without bottoming the rim, then adjusts for surface, casing, and weather.
Enter your setup to get a front and rear pressure range in PSI or BAR, the watts you lose by over-inflating, and a hookless safety cap. We call the output your Pressure Plan.
Gear up
Set pressure accurately
A pressure recommendation is only as good as the gauge you set it with. Verify low gravel and MTB numbers with a digital gauge, and go tubeless to run them safely.
- Floor pump with accurate gaugeA pressure recommendation is only as good as the gauge you set it with. Cheap pumps read high.View on Amazon →
- Digital tire pressure gaugeVerify low gravel and MTB pressures to the tenth of a psi, where a floor-pump dial is vague.View on Amazon →
- Tubeless conversion kitGoing tubeless lets you safely run the lower pressures this tool recommends for rough surfaces.View on Amazon →
- Tubeless sealantSeals small punctures at low pressure and reduces burping. Top up every few months.View on Amazon →
- Digital caliperMeasure your real inner rim width and mounted tire width so the balloon math is accurate.View on Amazon →
As an Amazon Associate we earn from qualifying purchases.
Find more free watts
Cycling Aero Calculator
See the watts and minutes each aero upgrade buys you for your position, speed, and event.
Turn watts into speed
Cycling Speed Calculator
Find your speed at any wattage and how much time each upgrade saves over your race distance.
How tire pressure is calculated
The Berto 15% tire-drop model sets the pressure that deflects a loaded tire about 15% of its height, the deflection that minimizes rolling resistance without letting the casing bottom out on the rim. The pressure each wheel needs rises with the load on that wheel and falls with the measured tire width. From that road baseline, this tool adjusts for surface, casing, wheel size, and weather.
| Input | Effect on pressure |
|---|---|
| Heavier rider or bike | Raises pressure (more load per wheel) |
| Wider measured tire | Lowers pressure (more air volume) |
| Rougher surface | Lowers pressure (more drop for grip and speed) |
| Stiffer casing or butyl tube | Raises pressure (resists pinch flats) |
| Wet conditions | Lowers pressure about 2.5 psi (grip) |
Tire pressure calculator FAQ
What tire pressure should I run?
There is no single number: correct pressure depends on the load on each wheel, your measured tire width, the surface, and your casing. The Berto 15% tire-drop model used here sets the pressure that deflects the tire about 15% under load, which minimizes rolling resistance without bottoming the rim. A 75 kg rider on 28 mm road tires typically lands around 70 to 80 psi rear and 60 to 70 psi front. Wider tires, rougher surfaces, and tubeless casings all lower that number.
Why is my front tire pressure lower than the rear?
Most of your weight sits over the rear wheel. On a road bike the split is roughly 40% front and 60% rear, so the rear tire carries more load and needs more pressure for the same 15% drop. Triathlon and TT positions shift slightly more weight forward (about 45/55). Running the front a few psi lower than the rear improves grip and comfort without raising rolling resistance, because the front carries less load.
Does a wider rim change my tire pressure?
Yes. A tire balloons wider on a wider internal rim, and a wider tire needs less pressure for the same 15% drop. A 28 mm tire on a 25 mm internal rim can measure 31 mm or more. This tool computes that measured width and uses it, not the labeled size, so a modern wide rim drops your optimal pressure by several psi versus an old narrow rim.
What is the maximum pressure for hookless rims?
Hookless tubeless rims are capped at 5.0 bar, which is 72.5 psi, under the current ETRTO and ISO standards. Above that the tire can blow off the rim because there is no bead hook to retain it. If your weight and tire size would call for more than 72.5 psi, run a wider tire rather than exceeding the cap. This calculator clamps hookless results at 72.5 psi and warns you when it does.
Can running too much tire pressure slow me down?
Yes, on anything but glass-smooth pavement. Above the optimal pressure the tire stops absorbing surface texture and instead bounces, so your body and bike absorb the vibration as wasted energy. This is called impedance or suspension loss. On rough gravel, over-inflating by 10 psi can cost 15 to 20 watts. On fresh asphalt the same over-inflation costs almost nothing, which is why surface choice matters as much as load.
Should I lower tire pressure in the wet?
Slightly. Dropping a couple of psi front and rear increases the contact patch and improves grip on wet roads and trails, with a negligible rolling-resistance cost. This tool subtracts about 2.5 psi from both wheels when you select wet conditions. Do not overdo it: going far below the recommended range raises pinch-flat and burping risk, especially with tubes.
Feedback
Missing something?
Tell us what you'd like to see added to this tool.