Getting the best gravel bike tire pressure is a bit of a black art and depends on lots of considerations, some dependent on your set-up, others on the conditions where you ride.
The optimum tire pressure is also important for your ride quality, grip and even safety, so it’s something you want to get right. Cyclocross racers who, like gravel bike riders, are also riding drop bar bikes off-road, are experts on tire pressure, obsessing about their tire tread and pressure before a race.
To some extent, getting your gravel bike tire pressure right is a matter of trial and error, so it’s worth experimenting. You also shouldn’t get fixated on only one value for your tire pressure on your gravel bike; it’s likely to vary with where you’re riding and will certainly be different if you swap tires to use the best gravel bike tires for the trail conditions. Deciding on the best tire size and tread pattern for your gravel bike can be equally challenging!
This guide will run through the factors to consider when dialling in the best gravel bike tire pressure for your rides, but first let’s look at what happens if you get it wrong.
What are the symptoms of the wrong gravel bike tire pressure?
It’s easy to get your gravel bike tire pressure wrong. If it’s too low, you risk sidewall damage, pinch flats (see below) and potentially damage to your wheel rim. Worst case, your tire can partially dismount from the rim.
Even if you don’t suffer these ride-busting problems, your ride quality might be poor, with the tire squirming under you as you ride, which can slow you down. It may burp, where the tire bead comes away from the rim letting air escape and losing you even more pressure.
If your tire pressure is too high, you’ll get bounced around a lot as you ride, which isn’t just uncomfortable, it will probably slow you down too. Your contact patch with the ground will be smaller, so you’ll get less traction, which may result in wheel slippage, and your tire will be more prone to sliding out, possibly increasing the risk of a fall.
A key consideration to take into account is how much you weigh. Finding the best gravel bike tire pressure is a balancing act and you need to avoid the pitfalls of either under- or overinflation.
A heavier rider will need to run increased tire pressure to account for the extra weight that their tires must support, which is equally true for road bike tire pressure.
Enve suggests adding another 1 to 2 psi for every 10lb increase in rider weight. That may not sound like a lot, but a 200lb/90kg rider will be running an over 50 per cent increase in gravel bike tire pressure over a 100lb/45kg rider.
Since your weight isn’t evenly distributed on the bike, you might want to run your front tire pressure a couple of psi lower than your rear tire too.
Don’t forget to factor in any luggage you’re carrying too - your bike will weigh a lot more if you’re set up with everything you need for bikepacking than if you’re just going for a short jaunt.
Tubed vs tubeless
Almost all gravel bike riders set their tires up tubeless. Among other advantages, from the perspective of setting your gravel tire pressure, the crucial one is that there’s no inner tube to get pinched between the tire’s sidewalls and the rim if you hit a rock.
That drastically reduces your chances of getting one of the most common causes of punctures when riding on uneven ground: the pinch flat. Also called a snakebike, this results in two parallel cuts in your inner tube that usually cause rapid pressure loss and are difficult to repair.
Since most gravel bike tire pressure recommendations assume you’re riding tubeless tires, if you do use inner tubes or need to fit one to fix a puncture, you should raise your tire pressure by around 5psi to compensate.
If you do want to run inner tubes or need to fit one to your gravel bike, TPU inner tubes like the Tubolito gravel range and Pirelli SmarTUBE are more puncture resistant than standard butyl tubes, although they’re considerably more expensive.
Next up, you need to consider your tire width. A wider tire will provide more air volume under you, letting you reduce the pressure over a skinnier tire. For a 160lb/73kg rider on a 23mm internal width rim, for example, Enve suggests a tire pressure of 42psi if you’re riding a 32mm tire, which it recommends dropping to 29psi for a 42mm tire.
Rim width also affects the volume of air inside a tire. We’re all aware of how much wider a tire can be than its claimed width when set up on the wider rims of the best road bike wheels. In fact, the effect can be so significant that, rather than just going with claimed width, 3T uses the width as measured, or WAM, to recommend the tires to use with its bikes and define its frames’ clearance.
So again this is a factor that will affect the best gravel bike tire pressure. Turning again to Enve’s recommendations, the brand suggests dropping the pressure by a couple of psi when moving from a 21mm to a 23mm internal width rim.
How soft the trail is is another factor to take into consideration when deciding the best gravel bike tire pressure to dial in before setting out. It’s another aspect of the too hard/too soft equation for optimum gravel bike tire pressure.
A soft surface or icy conditions call for lower tire pressure. This will increase grip, as the tire will conform more to the terrain. But if you’re riding hard, rocky trails, you’ll want a bit more air in your tire to ensure that you don’t bottom out on the rim or damage the tire’s sidewalls and cause the problems noted above.
A smoother surface might be best ridden at higher pressure. If your rides are principally tarmac but include some easy gravel stretches, you might be prepared to sacrifice some gravel grip and comfort for better progress when you’re on the road.
Another consideration to throw in is that really muddy conditions can often be tackled better with narrow tires than with wider ones, as the tire will sink further into the slop and may find more traction, rather than floating on its surface.
How you ride
If your riding style is conservative, you can probably get away with a softer gravel bike tire at lower pressure.
If, on the other hand, you like to catch air and bunny hop, your gravel bike tires are going to have to withstand the weight of you and the bike landing on them. That may increase the risk of a pinch flat or tire damage, so you may need to run higher tire pressure to compensate.
Gravel bike tire design
Some of the best gravel bike tires are built a lot tougher - and heavier - than others. If you’ve got a heavier tire, it’s likely to have more robust sidewalls, which are less prone to damage. They’re also likely to deflect less. That means that you can reduce tire pressure over a lighter weight tire. In fact, you may need to do so to ensure the best ride quality.
Gravel bike tire inserts
Finally, tire inserts give you a way to simultaneously get many of the benefits of both higher and lower gravel bike pressure. They reduce tire deformation, so that the risk of squirming, bottoming out, pinch flats and sidewall damage is reduced. You can still lower the tire pressure though, to improve your grip and handling. It may let you ride a flat more easily too.
The flip side is that an insert will add extra weight to your set-up and since it’s rotating mass, your ride feel and your bike’s performance might be compromised.
So, what is the best gravel bike tire pressure?
All of which hasn’t answered the original question, what's the best gravel bike tire pressure?
For a 160lb/73kg rider on a tubeless gravel bike tire of 35mm to 40mm, try starting off at around 35 to 40psi. Then you can fine-tune your gravel bike tire pressure to see what works for you. Most riders in most conditions should be able to drop from there, but if you hear and feel your rims bottoming out, add some extra air.
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