Tyre pressure calculator for road, gravel & MTB
Enter your weight, tyre width, rim, setup and surface. You get the pressure for your front and rear tyre in bar and psi.
Your bike and tyres
Bike including bottles, bags or backpack.
Width as printed on the sidewall. Inch sizes such as 2.4 are converted to mm.
Advanced: rim & weight distribution
The internal width is usually printed on the rim or listed by the manufacturer, e.g. “21C” or “622x25”. Hookless rims have a straight sidewall without a hook.
Your tyre pressure
How the calculator works out your tyre pressure
p = C · wheel load0.9 / width1.5 · factors
The calculation is based on measurements by the engineer Frank Berto. A tyre rolls fast and comfortably when it compresses by about 15% of its height under load. The pressure needed for that depends mainly on the load on the wheel and the tyre width.
First the calculator splits your total weight between the wheels. On a road bike the rear carries about 55%, on a gravel bike 56% and on a mountain bike 57%. At the front it adds 10–15% for braking and steering. Then it uses the tyre width as it actually measures on your rim, plus factors for tubeless, surface and wet roads. We checked the model against Berto’s data and the pressure charts of major tyre and wheel makers.
What determines the right tyre pressure
Wider tyres need less pressure
A wide tyre spreads the load over a larger contact patch, so it needs less pressure for the same compression. Going from 25 to 32 mm lowers it by about 27%. You get more comfort and grip. On rough tarmac you even roll faster, because the tyre soaks up bumps instead of lifting the whole bike.
Rim width changes tyre width
On a wider rim the same tyre sits wider. Each extra millimetre of internal rim width adds about 0.4 mm. A 28 mm tyre on a 21 mm rim measures closer to 29 mm. That is why the calculator asks for your rim under “Advanced”.
Tubeless, latex or butyl tube
Without a tube there are no pinch flats (snakebites) and the casing flexes more freely. So you can run about 6% less pressure tubeless, and about 3% less with latex or TPU tubes. Too little pressure still causes trouble without a tube. The tyre folds in corners, burps air or the rim bottoms out.
Hookless rims and the 5 bar limit
Hookless rims have no hook to hold the tyre bead. The ETRTO standard therefore limits pressure to 5 bar (72.5 psi) and requires hookless-approved tyres of at least 25 mm. If the calculated value is higher, the calculator shows a warning. A wider tyre solves it.
Fine-tuning your pressure
- 1Pump both tyres to the calculated starting value. Use a digital gauge, because floor pump gauges are often 0.2–0.3 bar out.
- 2Ride a loop you know well, with your usual surfaces, corners and descents.
- 3If the bike feels harsh and skittish or bounces over bumps, let out 0.1–0.2 bar. If the steering feels vague, the tyre squirms in corners or the rim bottoms out, add a little air.
- 4Check the pressure before every ride. Tyres lose noticeable air overnight, especially with latex tubes or tubeless.
Tyre pressure FAQ
What tyre pressure should I run on a road bike?
It mainly depends on your weight and tyre width. For a 75 kg rider, an 8 kg bike, 21 mm rims and butyl tubes on smooth tarmac, the calculator gives front / rear 5.2 / 5.7 bar (75 / 83 psi) for 25 mm, 4.5 / 5.0 bar (65 / 72 psi) for 28 mm and 3.8 / 4.2 bar (55 / 61 psi) for 32 mm. Tubeless is about 6% lower. The 7–8 bar that used to be common is no faster on modern, wider tyres. It just rides harder.
What tyre pressure for gravel?
For 40 mm tubeless tyres on 25 mm rims, a 75 kg rider and a 10 kg bike, the calculator gives front / rear 2.35 / 2.64 bar (34 / 38 psi) on hardpack, 2.15 / 2.41 bar (31 / 35 psi) on mixed surfaces and 1.97 / 2.21 bar (29 / 32 psi) on rough, loose gravel. Wider tyres need even less. Tubeless pays off on gravel, because without a tube you can go lower without getting pinch flats.
What tyre pressure should I run on an MTB?
For a 2.4 inch (61 mm) tubeless tyre on a 30 mm rim, a 75 kg rider and a 15 kg bike, the calculator gives front / rear 1.40 / 1.60 bar (20 / 23 psi) for XC, 1.48 / 1.68 bar (21 / 24 psi) for trail and 1.60 / 1.81 bar (23 / 26 psi) for enduro and downhill. For XC you run less pressure for grip. Enduro and downhill need more reserve against rim strikes.
Why less pressure at the front than at the rear?
When seated, the rear wheel carries more than half the total weight, on a mountain bike around 57%. With equal pressure the front tyre would be harder than it needs to be and grip less. Braking and steering put extra load on the front wheel, though. So the gap is smaller than the weight split, 9 to 12% in the calculator.
How much lower can I go with tubeless?
Without a tube there are no snakebite pinch flats and no friction between tube and tyre. The calculator therefore uses 6% less pressure for tubeless than for a butyl tube, and 3% less for latex or TPU tubes. Go much lower and the tyre can burp off the rim or the rim can bottom out.
What does hookless mean for tyre pressure?
Hookless rims have no hook to hold the tyre bead. Under the ETRTO standard they may be run at no more than 5 bar (72.5 psi), and only with tyres of at least 25 mm that are explicitly approved for hookless. The lower of the rim’s and tyre’s maximum pressures always applies.
How do I convert bar to psi?
1 bar equals 14.5 psi, 1 psi equals 0.069 bar. Examples: 2 bar = 29 psi, 4 bar = 58 psi, 5 bar = 72.5 psi, 6 bar = 87 psi. The calculator always shows both units.
How accurate is the calculated tyre pressure?
The calculator gives you a starting value based on measurements and manufacturer charts. Tyre model, casing, temperature and riding style shift the right pressure by a few percent. Check it with an accurate gauge, ride a loop you know and adjust in steps of 0.1–0.2 bar.