Quick answer
Gravel tires generally run lower than road tires and higher than most mountain bike tires. Many gravel riders end up somewhere in the 20s to 40s PSI, depending on tire width, total weight and surface. Treat the chart below as a first guess, then adjust.
Starting PSI by tire width
These are rough, rounded starting points for a rider with bike and gear totalling around 160 to 180 lb (about 73 to 82 kg) on tubeless tires and mixed gravel. Different brands’ calculators disagree, which is expected.
| Tire width | Smooth hardpack (PSI) | Rough or loose gravel (PSI) |
|---|---|---|
| 35 mm | 35 to 45 | 30 to 40 |
| 40 mm | 30 to 40 | 28 to 35 |
| 45 mm | 28 to 35 | 25 to 32 |
| 50 mm | 25 to 32 | 22 to 30 |
For tubed setups, many riders add a few PSI to reduce pinch flats. Always stay within the tire’s printed range. If you are choosing a width, see gravel bike tire width and clearance. For the broader picture across bike types, see our bike tire pressure chart.
Adjusting for weight and load
Heavier riders need more pressure. So does anything you add: bikepacking bags, a loaded rack, or a full hydration pack. As a loose rule, if you gain weight, add a little pressure and see how the bike feels, rather than making large jumps. Handling that feels vague or rim hits on rocks suggest the pressure is too low for the load.
Terrain
- Smooth, fast surfaces: a slightly higher pressure often feels quicker.
- Washboard and chunky gravel: a lower pressure can improve comfort and traction.
- Mud and sand: lower pressure can help grip, within what the tire and rim can tolerate.
Tubeless vs tubes
Tubeless tires can usually run lower because there is no tube to pinch against the rim. Going very low can still cause burping or rim damage, and it can let the tire squirm in corners. Tubed tires often need a bit more pressure to avoid pinch flats, but high pressure on rough gravel can feel harsh.
Front and rear
The rear usually carries more weight, so a rear tire a few PSI higher than the front is common. Some riders run them the same or reverse the split for loose descents. It is worth testing.
Rim and hookless limits
Rim width and type affect the pressure a tire can safely take. Hookless rims typically have a manufacturer-stated maximum, often lower than hooked rims, and a figure around 73 PSI (5 bar) is commonly quoted. Check your rim’s own specification before inflating, and never exceed the lowest maximum among tire and rim.
What is the 4 PSI rule?
The phrase is used in different ways by different writers, and there is no single standard definition that we can point to. In some contexts it refers to small adjustments, such as changing pressure in steps of a few PSI. Treat it as a rough habit rather than a rule, and make changes in small increments so you can feel the difference.
Dialing it in
- Pick the starting number from the chart.
- Check the pressure with an accurate gauge. See how to check your bike tire pressure accurately.
- Ride a familiar mixed route.
- Lower pressure a few PSI if the ride feels harsh or the bike skips over washboard.
- Raise it a few PSI if the tires squirm in corners, feel vague, or you feel the rim.
- Note the numbers for next time.
FAQ
What PSI should I run on my gravel bike? Many riders start in the 25 to 40 PSI range, depending on tire width, weight and terrain.
What PSI should 700c tires be? It depends on width. Narrower 700c road-width tires are much higher than 700c gravel tires. Use the width in the table above.
What is the recommended tire pressure for a 50 mm gravel bike tire? As a rough starting point, the mid 20s to low 30s PSI for a typical rider on tubeless, then adjust for load and terrain.