MTB and Gravel Tire Pressure: Setting It for Your Weight and Terrain

23 to 50 psi. That’s the range printed on the sidewall of a 29 × 2.40-inch mountain bike tire, the Kryptotal Re, in Continental’s 2026/27 catalog [1]. On paper, anything between those two numbers works. In practice, the right pressure depends mostly on you: your weight, the tire’s width, how it’s set up, and the terrain that day. Manufacturers’ charts give you a starting point, as long as you know what they assume, because they don’t all say the same thing.

What sets the pressure: weight, width, and setup

The “right” pressure depends largely on the weight the tire carries, Schwalbe explains: that of the rider and their luggage, with the bike itself counting for little [2]. The narrower the tire and the heavier the load, the more air you need; a wide tire gets by with less, and a tubelessNo inner tube: the tire seals against the rim with liquid sealant, which also plugs small punctures. setup can run a little lower [2].

Inflating is a trade-off. Higher pressure cuts rolling resistance on the road, wear, and the risk of flats; lower pressure brings comfort and grip [2]. Run too low for too long, it wears the tire out early and cracks its sidewalls [2]. With an inner tube, it also leaves you open to a pinch flatA flat caused by an impact: the tube gets pinched between the rim and an obstacle, leaving two small parallel cuts, hence the nickname “snakebite.”, and Michelin’s advice is then to raise the pressure [3]. A tubeless tire, DT Swiss notes, can run softer without the risk of pinching [4].

Then there’s the question of which weight to enter in a chart, and manufacturers don’t agree. ENVE, the wheel maker, starts from the rider’s weight with all their gear, on a bike of average weight [5]. SILCA’s calculator, from the pump maker, asks for the total weight: rider, bike, and luggage [6]. On an electric mountain bike, much heavier than a regular one, the gap between the two ways of counting gets bigger. Before you read a chart, check what “weight” means.

Mountain bikes: ENVE’s chart for a 2.4-inch tire

ENVE publishes a chart broken down by weight, with front and rear listed separately. Its numbers assume a tubeless setup; the ones below are for a 2.4-inch (61 mm) tire on a rim with a 30 mm inner width [5]. The chart doesn’t distinguish wheel size, 27.5 or 29 inches, which sometimes depends on frame size.

Two notes from ENVE change how you read it. Its rims have built-in pinch-flat protection, and its numbers account for that: on other wheels, you may need more air [5]. With a reinforced casing, double-ply or downhill, it suggests trying the low end of the range instead [5]. And tubes? Its charts don’t cover them. Among tire makers, two simple rules: tubeless can run a little lower, says Schwalbe, and a pinch flat means you need more air, says Michelin [2, 3].

Gravel: three manufacturers, three answers

For gravelRiding on unpaved roads and trails (gravel, dirt, forest roads) on a drop-bar bike with wide tires, somewhere between road cycling and mountain biking., ENVE gives a single number per row, with no front-rear split, again for tubeless. Here are its numbers for a rim with a 25 mm inner width [5].

SILCA’s calculator works differently. It looks for the fastest pressure on a given surface: the point past which impacts from the ground cost more energy than the tire’s flexing [8]. So it asks for total weight, surface, the tire’s measured width, speed, weight distribution, and casing type [6].

Two surprises. Weight barely matters: from 154 to 243 lb (70 to 110 kg), the pressure goes up only about 3 psi. And a butyl tube lowers the suggested number instead of raising it. SILCA makes it clear that its calculation is about speed, not pinch-flat protection, and warns that a wide tire on rough ground puts a standard tube at risk of pinching; the fix is then to go tubeless, or to run more air and give up a little efficiency [8].

Let’s run the numbers for one rider: 170 lb (77 kg) with gear, a 22 lb (10 kg) bike, a 40 mm tubeless tire. ENVE suggests 34 psi (2.3 bar) [5]. SILCA, on category 2 gravel and for 192 lb (87 kg) total, 36 psi up front and 37.5 psi in the rear (2.5 and 2.6 bar) [6]. Finally, tire maker WTB puts the sweet spot for a 40 mm gravel tire at around 40 to 45 psi (2.8 to 3.1 bar), without giving a weight, and tells riders to adjust for their style, terrain, and weight [7]. That’s an 11 psi (0.8 bar) spread from lowest to highest: each one assumes a different rim, tire, and goal.

Dry, muddy, rocky, or paved: fine-tuning for the terrain

Weight gives you the starting point; terrain does the fine-tuning. SILCA’s calculator makes it obvious: for 198 lb (90 kg) total and a 40 mm tubeless tire, the suggested pressure drops by about 14.5 psi (1 bar) between new pavement and the roughest of its gravels, which SILCA calls the worst surface in its calculator [6, 8].

On a mountain bike, Michelin notes that a very rocky trail may call for a different pressure, and that a higher pressure rolls better on easier ground [3]. WTB gives you the warning sign to watch for: if the tire compresses all the way to the rim on big hits, or folds in corners, it needs more air [7]. On very grippy ground (loam, slickrock, tacky trails), ENVE adds that the top of its range may not be enough, and recommends going up 5 to 10% at a time [5].

In mud or sand, the logic flips. Michelin observes that lower pressure can help you keep moving on very loose ground [3], and SILCA admits that its own number, 40 psi for a 33 mm cyclocross tire on its worst gravel, would be way too high in a muddy race: grip is what limits speed then [8]. On pavement, finally, a harder tire rolls more easily, Schwalbe points out [2]: that’s the first row of the table.

Front and rear: why the rear gets a little more

When you’re seated, you put more weight on the rear wheel. SILCA’s calculator assumes 47% of the weight up front and 53% in the rear on a gravel bike, 46.5% and 53.5% on a mountain bike; from that, it lowers the front pressure by 2.5 to 3% and raises the rear by 2 to 3% [6]. On a 40 mm gravel tire, that works out to about 1.5 psi (0.1 bar).

ENVE’s mountain bike chart points the same way, with up to 1 psi more in the rear [5]. Michelin recommends always running the front of a mountain bike slightly softer, but generally using the same pressure in both wheels of a road bike [3]. For gravel, its guide doesn’t say: ENVE’s chart gives a single number, SILCA’s calculator two.

PSI and bar: converting and measuring accurately

ENVE’s, SILCA’s, and WTB’s charts use psi, pounds per square inch; Schwalbe uses bar, and Continental’s catalog psi. The conversion fits on one line, but decimals trip people up fast: 29 psi is 2 bar, 36.3 psi is 2.5 bar, 43.5 psi is 3 bar.

You still have to read it right. The thumb test isn’t worth much: above about 29 psi (2 bar), Schwalbe warns, every tire feels pretty firm [2]. ENVE adds that pump gauges vary a lot from one model to the next, and that a valve core clogged with sealant throws off the reading [5]. How often? At least once a month, according to Schwalbe, which considers a loss of about 14.5 psi (1 bar) a month normal, faster at high pressure [2]. With tubeless, WTB recommends checking every time you ride [7].

Enlarge photo

The limits: sidewall, rim, and hookless rims

Charts give you a starting point; limits aren’t negotiable. The tire’s sidewall lists a minimum and a maximum: 34 to 72 psi (2.3 to 5.0 bar) for the 700 × 40 Terra Trail gravel tire, 23 to 50 psi (1.6 to 3.4 bar) for the 29 × 2.40 Kryptotal Re [1]. The rim has its own maximum too, often lower: at ENVE, 60 psi (4.1 bar) for the G23 gravel rim with a 32 to 40 mm tire, 40 psi (2.8 bar) for the G27 with a 42 to 50 mm tire [5]. When the two differ, the lower one applies [9].

HooklessA rim whose sidewalls lack the small lip that holds the tire’s bead. The ETRTO calls it TSS, for Tubeless Straight Side. rims add a limit of their own. Schwalbe publishes the table, which it says follows the ETRTOEuropean Tyre and Rim Technical Organisation, which sets dimension and usage standards for tires and rims in Europe.: it drops as the tire gets wider, and applies even if the sidewall promises more [10]. According to this table, a 40 mm gravel tire must not exceed 50.8 psi (3.5 bar) on a hookless rim, even if its sidewall says 72 psi, and a 2.4-inch (61 mm) mountain bike tire 36.3 psi (2.5 bar) [10].

SILCA’s calculator even shows a warning above 70 psi: in its view, a hookless rim shouldn’t be used above 72 psi [6]. That’s within half a psi of the maximum the ETRTO and ISO set for a 28 mm road tire on this type of rim, 72.5 psi or 5 bar, ENVE points out [11]. For a gravel or mountain bike tire, the limit is much lower, as the diagram below shows.

Enlarge diagram

The rule to remember fits in one sentence: the chart gives you a starting point, the terrain adjusts it, and the lower of the tire’s and the rim’s maximums never gets crossed.

Worth watching

GMBN Tech walks through what tire pressure changes on the trail, from traction, cornering, and comfort to rider weight, terrain, tire width, and weather, so you can dial in your own number.

The video is hosted by YouTube (Google): nothing loads until you play it, and Google may then set cookies.

Julien de Jurquet

Vans, RVs, biking and calculators

Julien de Jurquet writes for Outfarer about camper vans, RVs, biking, and calculators. He reads manuals cover to cover and never lets a number slide without its unit, so your choices rest on math, not promises.

All their articles