Gravel tire pressure, by weight and width
Find your all-in weight down the side and your tire width across the top. That is your starting pressure, front and rear.
Then read the part underneath, because one tire size moves that number as far as a hundred pounds of rider does, and almost nobody says so.
Start here, then ride it
All-in weight means you, the bike, and everything on it — bottles, bags, tools, the lot. Weigh yourself holding the loaded bike if you want to be quick about it. Tire width is what is printed on the sidewall.
Front / rear psi · tubeless · 25 mm internal rim · mixed gravel
| All-in weight | |||||||
|---|---|---|---|---|---|---|---|
Tap a weight and a width to hold both axes.
Get the figure for your exact weight and width
These are tubeless on a 25 mm internal rim at a mixed gravel pace — some hardpack, some loose, nothing extreme. Running tubes, a different rim, or rougher ground moves every one of them, which is what the calculator is for.
10 mm of tire is worth 100 lb of rider
This is the thing most gravel pressure advice buries. At 190 lb all in, going from a 35 mm tire to a 45 mm one drops your rear pressure by 9 psi — exactly as far as the whole 100 lb of this table moves it on a 40 mm tire, 140 lb to 240 lb. One tire size, a purchase you could make this week, against a hundred pounds of rider.
Which is why a chart keyed only to rider weight cannot work. A 240 lb rider on a 50 mm tire wants 38 psi; a 140 lb rider on a 32 mm tire wants 46 psi. The heavier rider runs softer, by a margin no weight-only chart can express — both numbers are in the table above.
Your rim changes the width of your tire
A 40 mm tire is not 40 mm. Mount it on a wider rim and the casing spreads, the real width goes up, and the pressure it wants comes down. The engine corrects for this from your internal rim width, which is the measurement between the bead walls — not the outside of the rim, and not the number in the marketing copy.
If you have callipers, measure the tire inflated and on the wheel and enter that instead. A measured width skips the correction entirely, because there is nothing left to estimate.
A tube makes it firmer, not softer
If you are running tubes, every number above goes up. Not down — up. A tube carries part of the load the casing would otherwise carry alone, and the air has to make up the difference. On these tires it is worth a few psi, and it is the one adjustment riders most often get backwards. How much, and why it runs that way.
The table is a starting point, not an answer
Ride it and pay attention to two things. If the bike is skittering off line on loose ground and your hands are tired after an hour, you are too hard. If the tire is squirming under you in corners or you are hearing the rim on rocks, you are too soft.
Move two psi at a time and ride the same ground again. Two psi is roughly the smallest change you can actually feel on gravel, and changing more than that at once means you learn nothing about which direction was right.