SRAM AXS Tire Pressure Guide
Compute tire pressures following the SRAM AXS methodology for hookless and hooked rims. Essential for modern tubeless road and gravel setups.
About
Modern wheel manufacturing has shifted toward hookless (straight side) rim profiles. This design simplifies carbon molding and reduces weight. It requires strict adherence to maximum pressure limits to prevent tire blowouts. The ETRTO standard for hookless rims limits pressure to 72.5 PSI (5 bar). This calculator mimics the algorithm used by SRAM and Zipp for their current generation wheels. It accounts for the casing pliability. Thin casings require higher pressure to support the sidewall. Reinforced casings provide self-support and allow for lower air pressure. Always check your tire manufacturer's compatibility chart before riding hookless rims.
Formulas
The calculator uses a piecewise function that defines a "baseline" pressure for a standard 75kg rider and scales linearly based on system weight deviation. The rim profile applies a constraint limit.
Volume compensation for rim width Wrim follows the relation:
Reference Data
| Internal Width (mm) | Recommended Tire Range | Hookless Compatible? | Max Pressure (PSI) |
|---|---|---|---|
| 19 | 25mm − 32mm | Depends on Brand | 110 (Hooked) |
| 21 | 28mm − 42mm | Yes | 72.5 (Hookless) |
| 23 | 28mm − 50mm | Yes | 72.5 (Hookless) |
| 25 | 30mm − 2.2" | Yes | 72.5 (Hookless) |
| 27 | 40mm − 2.4" | Yes | 72.5 (Hookless) |
| 30 | 2.1" − 3.0" | Yes | 45 |
| 32 | 2.3" − 3.0" | Yes | 40 |
| 35 | 2.6" + | Yes | 35 |