Gravel tire pressure guide
Updated July 2026
Gravel is the hardest surface to guess pressure for: the ground changes from packed dirt to chunky rock inside a single ride, and the tires are wide enough that a few PSI changes how the bike behaves. This guide explains what actually sets your pressure, how to adjust it for the terrain in front of you, and how to use the calculator to get a starting number you can trust.
Open the pressure calculatorTypical starting pressures for gravel
| Measured width | Dry, packed dirt | Mixed / loose gravel | Chunky rock, roots |
|---|---|---|---|
| 35 mm | 45–48 psi / 3.1–3.3 bar | 42–45 psi / 2.9–3.1 bar | 38–42 psi / 2.6–2.9 bar |
| 40 mm | 38–41 psi / 2.6–2.8 bar | 35–38 psi / 2.4–2.6 bar | 32–35 psi / 2.2–2.4 bar |
| 45 mm | 33–36 psi / 2.3–2.5 bar | 30–33 psi / 2.1–2.3 bar | 27–30 psi / 1.9–2.1 bar |
| 50 mm | 29–32 psi / 2.0–2.2 bar | 26–29 psi / 1.8–2.0 bar | 23–26 psi / 1.6–1.8 bar |
Rough starting points for a 180 lb / 82 kg loaded weight on 700c wheels at a steady endurance pace. Run the calculator for numbers matched to your own weight, casing and pace — these are only a sanity check.
Measure the tire, don't trust the label
A tire marked 40 mm can sit anywhere from 38 to 44 mm once it is mounted, because the rim's internal width stretches the casing. Pressure follows air volume, and volume follows the real width, so a 3 mm error is easily 3–4 psi of error.
Inflate the tire, leave it overnight, then measure the widest point of the casing with a caliper. Use that number in the calculator — every recommendation on this page assumes measured width, not printed width.
What actually decides your gravel pressure
Four inputs do almost all the work. Everything else is fine-tuning:
- Loaded weight — rider, bike, bottles, bags and tools. Bikepacking luggage can add 10 kg and needs real pressure to match.
- Measured tire width and rim diameter — the air volume you are riding on.
- Surface roughness — rougher ground means more impedance losses, so lower pressure is genuinely faster, not just more comfortable.
- Pace — higher speed means bigger impacts and more casing deflection, so fast riders need a little more pressure than the same rider spinning along.
Why lower is usually faster on gravel
On smooth tarmac, a harder tire rolls faster. On gravel the opposite happens past a certain point: every stone the tire cannot absorb pushes the bike and rider upward, and that energy is lost as vibration. This is rolling impedance, and it climbs steeply once the tire is too hard for the surface.
The fast pressure is the lowest one that still protects the rim, keeps the tire stable in corners and doesn't feel vague under power. That is exactly what the calculator targets — a front and rear number balanced around your weight distribution rather than one pressure for both wheels.
Front and rear should never match
Roughly 40 % of your weight sits on the front wheel and 60 % on the rear when you are on the hoods. Running the same pressure in both means the front is too hard — which is where grip, steering feel and comfort come from — while the rear is closer to correct.
Expect a 2–4 psi (0.15–0.3 bar) gap on gravel, more if you carry a saddle bag. The calculator does this split for you and can even handle different widths front and rear.
Casing, tubeless and inserts
A supple tubeless casing can be run several PSI lower than a tube-type tire, because there is no inner tube to pinch and the casing conforms instead of bouncing. Tubes need a safety margin — pinch flats happen when the casing bottoms out on the rim.
Foam inserts add another few PSI of headroom at the bottom end, which is useful on rocky terrain. If you keep bottoming out or burping the tire, the fix is a wider tire before it is more pressure.
Adjusting for conditions
Start from the calculator's number, then shift it for the day:
- Wet, muddy or loose-over-hard: drop 2–3 psi (0.15–0.2 bar) for grip.
- Sharp, chunky rock at speed: add 2–3 psi to protect rim and casing, or fit a wider tire.
- Bikepacking load: recalculate with the full loaded weight rather than adding pressure by feel.
- Cold morning start: pressure rises as the tire warms, so setting on the low side is safe.
- High altitude or a long descent: check pressure at the top, not in the car park.
How to test it on the bike
Change one thing at a time. Ride the same rough section twice, two PSI apart, and note whether the bike tracks straighter and feels calmer or starts to wallow and squirm in corners. When it wallows, you have gone one step too far — come back up 2 psi and stop there.
Write the winning numbers down. In Pressure Lab Cycling you can save a setup in the garage, mark it as your current setup and have it appended automatically to your Strava activities, so the tire, width and pressure you rode is recorded with the ride.
Common questions
- What tire pressure should I run on a gravel bike?
- Most riders on 40 mm tubeless gravel tires land somewhere between 28 and 40 psi (1.9–2.8 bar), with the front a couple of PSI below the rear. The exact number depends on your loaded weight, measured tire width, surface and pace — run those through the calculator instead of copying a friend's setting.
- Is lower pressure faster on gravel?
- Up to a point, yes. Lower pressure lets the tire absorb the surface instead of bouncing the bike, which reduces rolling impedance. Below the optimum the casing deflects too much, the tire feels vague and pinch-flat risk rises, so speed drops again.
- Should front and rear pressure be the same?
- No. The rear wheel carries more weight, so it needs more pressure — typically 2–4 psi (0.15–0.3 bar) more than the front on gravel.
- How much lower can I go with tubeless?
- Tubeless usually allows roughly 3–6 psi less than the same tire with a tube, because there is no tube to pinch. Watch for burping in corners — that is the signal you have gone too low for your rim and casing.
- Do I need to change pressure for bikepacking?
- Yes. Luggage is extra loaded weight, and pressure scales with it. Recalculate using rider plus bike plus all the bags rather than guessing an extra few PSI.