Question 1

What PSI and BAR should I run on a gravel bike?

Accepted Answer

For a 175 lb (79 kg) rider on 40mm tubeless tires, hardpack gravel runs about 40.5 PSI / 2.8 BAR front and 42.5 PSI / 2.9 BAR rear. Moderate mixed gravel drops to roughly 37 PSI / 2.6 BAR front and 38.5 PSI / 2.7 BAR rear, and loose or rocky gravel drops further to about 32.5 PSI / 2.2 BAR front and 34.5 PSI / 2.4 BAR rear. Lighter riders and wider tires both push these numbers lower. Use the calculator above for your exact weight and measured width.

Question 2

Is this gravel calculator based on SILCA's methodology?

Accepted Answer

Yes. It runs SILCA's impedance-breakpoint formula, the same one built for its pro-tour tire pressure calculator. That methodology finds the exact PSI where more air stops improving rolling resistance and starts costing you speed through vibration losses. The formula itself is unchanged; only the inputs are narrowed to gravel-only surface categories, tire widths and wheel sizes.

Question 3

What's the difference between the gravel surface categories in this calculator?

Accepted Answer

Cat 1 is hardpack dirt or light gravel with minimal surface texture: the smoothest gravel condition, and the highest recommended pressure. Cat 2 is moderate mixed gravel, the most common all-around gravel-ride surface. Cat 3 is loose or rocky gravel, where traction and vibration absorption matter more than rolling efficiency. Cat 4 is deep, chunky or loose gravel, the roughest condition. That's where the calculator drops pressure the most, so the tire can conform around obstacles instead of bouncing over them.

Question 4

How much lower should tubeless gravel tire pressure be than tubed?

Accepted Answer

This calculator's casing input already reflects that difference: switching a 175 lb rider's 40mm hardpack (Cat 1) setup from high-performance tubeless to a mid-range butyl tube drops the recommended pressure from 42.5 PSI rear to 40 PSI rear, a difference of about 2.5 PSI. Tubeless removes pinch-flat risk at a given pressure, which is why most gravel riders who go tubeless then run 3–8 PSI lower in practice than this baseline for extra grip, not because the tube itself demanded more air.

Question 5

Should gravel bike front and rear tire pressure be different?

Accepted Answer

Yes. Gravel bikes carry roughly 47% of system weight over the front wheel and 53% over the rear, so the rear tire needs 1.5–2 PSI more than the front to achieve the same tire drop and contact patch shape at both ends. This calculator applies that 47/53 split automatically to every result, so you never need to guess or calculate it yourself.

Question 6

What tire width does this calculator support for gravel?

Accepted Answer

28mm through 55mm measured width, covering fast gravel/all-road tires (28–35mm) through standard gravel (38–45mm) up to plus-size gravel setups (45–55mm) run on some 650b bikes. Always enter the tire's actual inflated measured width on your rim, not the number printed on the sidewall.

Question 7

Why doesn't this calculator ask about road or MTB surfaces?

Accepted Answer

This tool is scoped specifically to gravel riding. It only offers the four gravel surface categories (hardpack through chunky/loose) and only 700c or 650b wheel sizes, since those cover essentially every gravel bike sold. Dedicated road and mountain bike tire pressure calculators use different surface and casing inputs suited to those disciplines.

Question 8

How is this different from a static gravel tire pressure chart?

Accepted Answer

A static chart cross-references your weight and tire width against a fixed table and rounds you into the nearest bracket. This calculator runs the SILCA impedance-breakpoint formula directly on your inputs: rider weight, measured tire width, surface roughness, casing stiffness and wheel diameter, all together. It only offers gravel categories, so you're not filtering a general-purpose road/MTB/gravel tool to find the section that applies to you.

Question 9

Does this calculator work for Pirelli, Schwalbe, Pathfinder or other gravel tires?

Accepted Answer

Yes. The calculator's output is based on rider weight, measured width, surface and casing stiffness, not tire brand, so it applies to any gravel tire, including Pirelli Cinturato Gravel, Schwalbe G-One, Specialized Pathfinder TLR, Vittoria Terreno, and WTB Riddler or Resolute.

Question 10

Do I need to know my rim's internal width to use this calculator?

Accepted Answer

No. Rim internal width matters because it changes how wide your tire actually measures once inflated, but this calculator asks for that measured width directly, so the rim's effect is already baked into your input. You don't need a separate rim-width lookup step the way some static pressure charts require.

Question 11

How does this calculator work for mixed gravel and road rides?

Accepted Answer

Start with the calculator's gravel number, then add 1–3 PSI (0.1–0.2 BAR) if the ride leans more toward rolling fast on pavement than floating over rough sectors. Riders who spend most of a route on tarmac and only duck onto occasional gravel connectors usually land closer to their normal road pressure minus 5–10 PSI. Treat the calculator's output as the anchor point and adjust toward road or gravel depending on which surface actually dominates your route.

Question 12

What tire pressure should I run for Unbound Gravel or other long gravel races?

Accepted Answer

Unbound Gravel's Kansas limestone roads are mostly fast but turn genuinely rough in sections, so it sits between this calculator's Cat 3 and Cat 4. Riders in the 160–180 lb (73–82 kg) range commonly race 40–45mm tubeless tires in the high 20s to low 30s PSI (roughly 1.9–2.2 BAR), adjusting down for mud years and up for a dry, fast course. Run the calculator's Cat 3 or Cat 4 output as your baseline, then confirm it on terrain close to what you'll actually race rather than changing pressure the morning of the event.

Question 13

Will this work for my Canyon, Trek or Specialized gravel bike?

Accepted Answer

Yes. The output depends on rider weight, tire width, surface and casing, not frame brand, so it applies the same way on a Canyon Grail or Grizl, Trek Checkpoint, Specialized Diverge, Giant Revolt, Santa Cruz Stigmata or anything else with modern gravel wheels and tires. Just stay within whatever pressure limits your specific rim and tire manufacturers print.

Question 14

How does this compare with what people on Reddit and gravel forums run?

Accepted Answer

Reasonably closely, once you account for personal preference. Most riders in the 150–190 lb (68–86 kg) range on 40–45mm tubeless tires end up within about 2–5 PSI (0.1–0.3 BAR) of this calculator's number after a few rides of trial and error. Use the calculator to skip the trial-and-error that lands people way too high or too low, then let your own feel for grip, speed and comfort make the final call.

Gravel Tire Pressure Calculator

Get Your Gravel Tire Pressure

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