The modern model: rider weight, tire width, surface, and tubeless setup. With a live calculator and the real-world corrections.
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A tire at the right pressure is faster, safer, and more comfortable. Over-inflate and grip disappears, especially in corners and over rough surfaces. Under-inflate and you bleed watts to rolling resistance, then catch a pinch flat.
There is no single correct number for everyone. The right answer depends on your weight, the bike's weight, the tire width, the surface, and whether you run a tube or tubeless.
Josh Poertner — formerly Zipp's chief engineer, now running Silca — published the Pro Tire Pressure Calculator that has become the de-facto industry standard. SRAM released their own guide in 2023 using essentially the same model.
The core idea is simple: pressure scales with per-wheel load and inversely with tire width to the power 1.4. One formula spans 23 mm road tires through 50 mm gravel rubber, no lookup tables required.
🔵 Калькулятор давления в шинах
Распределение веса: front 40% / rear 60%
Стартуй с этих значений, подбирай ±5 psi по ощущениям.
Silca Professional Pressure Calculator + SRAM Tyre Pressure Guide; Jan Heine (Compass) research.
Рекомендации общие. Финальная настройка — по ощущениям сцепления и комфорта.
Weight distribution on a road bike is typically 40 % front / 60 % rear because the saddle sits behind the bottom bracket. On gravel the rider shifts slightly further back (58/42) to keep the rear wheel planted on loose surface.
Result: the rear wheel carries more load and wants roughly 5 psi more pressure than the front. Pump both tires equal and you under-inflate the rear, over-inflate the front, and lose both comfort and grip.
| Condition | Adjustment | Reasoning | |
|---|---|---|---|
| Wet road | −10% | Grip becomes more valuable than rolling speed; softer tire forgives a small slide | |
| Hardpack gravel | −22% | The tire absorbs micro-vibration and saves the rider hours of buzz on long days | |
| Loose gravel / rocks | −34% | Wider contact patch tracks instead of skipping across the surface | |
| Latex tube vs butyl | −5% | Latex deforms more readily, run a touch lower without bottoming out on the rim | |
| Tubeless setup | −12% | No tube to pinch — push pressure meaningfully lower for compliance and grip |
Once pressure is dialled, check that your tire width fits the frame. Most modern road frames clear 32–34 mm; gravel frames go to 45–50 mm. Look up the max tire clearance in the geometry guide of any frame in our catalog. A narrower tire at the right pressure outruns a wider one at the wrong pressure.
Sources: Silca Professional Pressure Calculator (Josh Poertner). SRAM Tyre Pressure Guide. Heine, J. (Bicycle Quarterly, 2019). «Wide Tires at Low Pressure» — empirically grounded research from the Compass/Rene Herse program.
