Cluster 10 · Tires

MTB bike tires

How much pressure should I run? The honest answer isn't a number: it's a range that depends on your weight, on the tire's real width, on the rim, on the casing and on the terrain. Here is the whole MTB tire from scratch — and the calculator that closes your range.

Pressure is not a numberThe pillar: why the correct pressure is a range with uncertainty, not a figure from a chart. The philosophy that organizes the whole cluster. ▶ PSI Pressure CalculatorThe asset: enter weight, width, rim and discipline and it gives you your range per wheel — with the uncertainty stated. Validated against the census of measured tires. Pressure by weightSystem weight pushes the range up, but doesn't fix a number. Why generic charts fail. Pressure by discipline (XC/Trail/Enduro/DH)How the impact and speed of each discipline move the range — and why DH isn't what you think. Front vs rear pressureThey aren't equal: the rear carries more, the front seeks grip. How far to split them. Tubeless pressureHow low you can go without a tube and why the reduction isn't a fixed "−3 psi". Minimum pressure and burpingWhere the floor is: the bead unseats and air escapes. The limit nobody models in Spanish. Pressure 29 vs 27.5Why the small wheel asks for more air — and the discrepancy between reference calculators. Pressure with insertsHow much you can really drop with CushCore/Rimpact and why not all inserts allow the same. Internal rim widthThe rim changes the profile and the real width of the tire — and with it the pressure range. ETRTO: how to read the sidewallWhat "57-622" means and why it's the only measurement that doesn't lie. Air volumeVolume is what really holds you up: why the same weight asks for less pressure in a wider tire. TPI and the casingThreads per inch: stiffness vs flexibility, and why it changes your starting pressure. Casing types (EXO/DD/DH)A reinforced casing runs lower than a light one at the same weight. Why. Hookless vs hooked: limitsThe 5 bar / 72.5 PSI (ETRTO) ceiling that isn't negotiable, and why it exists. Tubeless setup step by stepSealant, valve, rim tape — and why once you finish, your pressure is no longer the tube one. Inserts: types and setupCushCore, Rimpact, Nukeproof… what they do, how they mount and their reduction factor. Tubeless vs tubeThe pressure difference isn't always "−3 psi": it depends on weight, volume and discipline. 29" tiresRollover, longer contact patch and why it usually runs lower than 27.5. 27.5" tiresLess volume, more maneuverable — and what it asks of pressure compared to the 29. Rolling resistanceThe paradox: more pressure is NOT faster on the mountain. Where the optimum is. Grip and contact patchLess pressure = more contact patch = more grip… with a limit. What it is. Real vs nominal width (the 2.4" myth)Why your tire doesn't measure what it says — with the census of measured tires.

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