Bike Tire Pressure Charts
Front / rear psi at the 15% tire drop · smooth surface, tubes, standard casing · tubeless ≈ 4% less, rough surface ≈ 6% less · hookless rims: never exceed 72.5 psi · pedaltoolbox.com/calculators/tire-pressure
What psi should my bike tires be?
Two numbers decide it: the weight on each wheel, and the width of the tire carrying it. Everything else — surface, casing, tubes — is a correction on top. The calculator sizes each tire to sag about 15% of its height under load, the drop where a tire grips and rolls its best, then splits the result front and rear because your rear wheel carries more of you. For a 165 lb rider on 28 mm road tires that lands at 56 psi front / 63 psi rear — not the 100+ psi printed on the sidewall, and that's the point.
On a perfectly smooth drum, harder tires roll faster. On real roads there's a breakeven point: above it, the extra pressure stops saving casing flex and starts hammering the bike (and you) with vibration, which costs more watts than it saves. Every modern pressure study — SILCA's and Rene Herse's included — finds the same shape. That's why the pro peloton quietly moved from 110 psi to the 60s and 70s.
Road bike tire pressure by weight and tire size
Road — front / rear psi
| Rider | 25 mm | 28 mm | 30 mm | 32 mm |
|---|---|---|---|---|
| 140 lb | 58 / 66 | 49 / 55 | 43 / 49 | 39 / 44 |
| 165 lb | 67 / 76 | 56 / 63 | 50 / 57 | 45 / 51 |
| 190 lb | 77 / 86 | 64 / 72 | 57 / 64 | 52 / 58 |
| 215 lb | 86 / 97 | 71 / 81 | 64 / 72 | 58 / 65 |
Front / rear psi, computed by the calculator above: rider plus a typical 19 lb bike, smooth pavement, tubes, standard casing, rims at the width the tire label assumes. Wider rim or tubeless? Use the calculator — both lower the number.
Gravel tire pressure
Gravel — front / rear psi
| Rider | 38 mm | 42 mm | 45 mm | 50 mm |
|---|---|---|---|---|
| 140 lb | 26 / 32 | 22 / 27 | 20 / 24 | 17 / 20 |
| 165 lb | 30 / 37 | 26 / 31 | 23 / 28 | 19 / 24 |
| 190 lb | 34 / 42 | 29 / 36 | 26 / 32 | 22 / 27 |
| 215 lb | 38 / 47 | 32 / 40 | 29 / 36 | 25 / 30 |
Smooth gravel, tubes, 21 lb bike. For washboard or chunky surfaces switch the calculator to rough (about 6% lower); tubeless takes another 4% off safely.
Mountain bike tire pressure
Mountain — front / rear psi
| Rider | 2.2″ | 2.35″ | 2.5″ |
|---|---|---|---|
| 140 lb | 16 / 19 | 14 / 17 | 13 / 15 |
| 165 lb | 18 / 22 | 16 / 20 | 14 / 18 |
| 190 lb | 20 / 25 | 18 / 22 | 16 / 20 |
| 215 lb | 22 / 27 | 20 / 25 | 18 / 22 |
Trail riding, 30 lb bike, tubes — most MTB setups are tubeless, which supports a few psi less. Below ~18 psi without an insert, rim strikes become the limit before grip does.
One page, all three charts, for the garage wall next to the pump.
Why wider rims mean lower pressure
A tire's labeled width assumes the narrow rim it was measured on. Mount that same tire on a modern wide rim and the casing spreads — roughly 0.4 mm of real width for every extra millimeter of internal rim width. Wider tire, bigger air chamber, less pressure needed. Same tire, same rider, four rims:
| Internal rim width | 28 mm tire measures | Front / rear psi |
|---|---|---|
| 19 mm | 28 mm | 56 / 63 |
| 21 mm | 28.8 mm | 54 / 61 |
| 23 mm | 29.6 mm | 51 / 58 |
| 25 mm | 30.4 mm | 49 / 56 |
165 lb rider, 28 mm labeled road tire. This is why "what pressure for 28s?" has no single answer — and why the calculator asks about your rim.
The hookless rim pressure limit
Hookless rims — most carbon tubeless road and gravel rims made in the last few years — have no bead hook holding the tire on. The industry standard (ETRTO) caps them at 72.5 psi, hard: above that, a tire can blow off the rim, and it happens at exactly the moment you least want it to. This calculator enforces the cap instead of footnoting it. If your math comes out capped, the fix isn't more air — it's more tire: a heavier rider on 25s is a comfortable, faster rider on 30s at 60 psi. Check both your rim's and tire's stated hookless compatibility; brands publish lists.
A typical 28 mm road tire prints "max 102 psi" on the casing. That's the pressure the tire can safely hold on a hooked rim — a legal limit, not advice. The same tire under a 165 lb rider rides best around 63 psi rear. Inflating to the sidewall max is the single most common pressure mistake in cycling, and it makes the bike slower and harsher at the same time.
Tubeless vs tubes: how much lower can you go?
Tubeless removes the pinch-flat: no tube to trap between rim and rock, so the pressure floor drops. The calculator takes about 4% off — 63 psi rear becomes 61 with the same setup — and on gravel and trail you can chase grip further down by feel. The practical limits that remain: rim strikes, tires squirming under cornering load, and burping air on hard hits. If you feel any of the three, add 2–3 psi back.
How we calculate it — and when to trust your hands
The model is the classic 15% tire-drop standard (Frank Berto's work), expressed as a power law of wheel load and measured casing width, then calibrated against the modern data-driven calculators rather than the old inflate-it-hard habit. Rim width adjusts the real casing width; surface, casing and tubeless scale the result; the hookless cap is enforced last. Every result shows its math. It's a starting point with real error bars: pump gauges routinely read ±5%, and your hands are the fine-tuning instrument. Ride it, then move 2–3 psi at a time — lower if it chatters and stings, higher if it wallows in corners. A 165 lb rider who swaps 28s (56/63 psi) for 32s (45/51 psi) isn't cheating — that's the same 15% drop in a bigger air chamber.