Bike tyre pressure calculator for road, gravel and mountain bikes
This bike tyre pressure calculator suggests front and rear pressures, in psi and bar, from your weight, your bike’s weight, the tyre width and the surface you ride. It uses the 15% tyre-drop method published by engineer Frank Berto: the tyre should squash by about 15% of its width under load, which balances rolling speed, comfort and grip.
Because the rear wheel carries more weight, the rear tyre needs more air than the front. The calculator splits the load by bike type, then keeps the answer inside the maximum and minimum printed on your tyre and rim — those limits always win. It runs in your browser.
How to find your tyre pressure
- Choose kg or lb, and Inner tubes or Tubeless.
- Enter the Rider weight and Bike and luggage, and pick the Bike type to set the front/rear weight split.
- Enter the Tyre width in mm or inches and choose the Surface, which sets the tyre drop target.
- Under Printed limits, enter the tyre’s maximum (and minimum, if printed), the rim type and any rim maximum.
- Pump to the front and rear pressures shown, using a gauge you trust, then fine-tune by feel.
Bike Tyre Pressure Calculator features
Front and rear
Wheel loads from published weight splits: racing 40/60, touring 45/55, city 35/65.
Published data
Matches Berto’s figures for 19–37 mm road tyres and Bicycle Quarterly’s worked example.
Limits built in
Caps at the tyre or rim maximum and the 5 bar hookless limit, and warns when it does.
Surface and tubeless
Softer drop targets for rough roads and gravel; with inner tubes the drop is held at 17% to limit pinch flats.
Width comparison
Pressures for 23 mm to 2.4 in tyres at your weight, to help choose a width.
How the tyre-drop method works
Berto loaded 50 tyres with a hydraulic jack, measured how far each dropped at different pressures, and plotted the pressure that gives a 15% drop for each width and load. For a 200 lb (91 kg) rider and bike, he gives 136 psi for 19C, 126 for 20C, 106 for 23C, 88 for 25C, 76 for 28C, 60 for 32C and 46 psi for 37C tyres. He notes 13% gives a firmer, faster feel and 17% a more comfortable ride.
This calculator interpolates between those widths, scales for your wheel load using Bicycle Quarterly’s example (45 kg and 55 kg wheel loads: 20 mm tyres 125 and 155 psi, 37 mm tyres 45 and 53 psi), and adjusts for other drop targets in proportion. Above 37 mm it extrapolates on the assumption that the contact patch grows with width to the power 1.5 — sensible, but not measured.
Worked example: a 75 kg rider on a 10 kg road bike with a 40/60 split puts 34 kg on the front and 51 kg on the rear. On 28 mm tyres that gives about 58 psi front and 85 psi rear (4.0 and 5.9 bar).
Surfaces, tubeless and wide tyres
- Smooth tarmac: 15%, Berto’s target. Rough roads: 17%, the softer end of his range.
- Gravel (18%) and trails (20%) are this calculator’s own starting points for more grip, not Berto’s figures — Berto said the 15% rule does not suit mountain bike tyres.
- With inner tubes deep drops risk pinch flats, so presets stop at 17%. Tubeless tyres cannot pinch a tube and are often run softer.
- Hookless rims must not exceed 5 bar (72.5 psi), and often less for wider tyres — follow the rim maker.
Bike Tyre Pressure Calculator FAQ
What tyre pressure should I run on my road bike?
It depends on your weight and tyre width. With the 15% drop method, an 85 kg rider and bike on 28 mm tyres needs about 58 psi front and 85 psi rear. Enter your own figures in the bike tyre pressure calculator above.
Should the front tyre have less pressure than the rear?
Yes. The rear wheel usually carries 55–65% of the weight, so it needs more pressure for the same tyre drop.
Do wider tyres need less pressure?
Yes, much less. In Berto’s figures for 100 lb per wheel, a 25 mm tyre needs 88 psi while a 32 mm tyre needs 60 psi for the same drop.
What pressure for tubeless tyres?
The same drop target works, but tubeless tyres can run lower without pinch flats, which is why the gravel and trail presets go deeper with tubeless.
Can I go above the maximum on the tyre?
No. Never exceed the tyre’s or rim’s printed maximum. If the calculator caps your pressure, a wider tyre is the safer fix.
How do I convert psi to bar?
Multiply psi by 0.0689 (1 bar = 14.5 psi). The calculator shows both; for other units use the pressure converter.