Is a wider tire with lower pressure faster?

Yes. A wider rim shape paired with a wider tire promotes less rolling tire deflection, resulting in lower rolling resistance. By creating a wider tire bead interface in relation to the outside rim width, we can offer a more aero rim-to-tire transition. A wider tire bead interface also allows for a wider tire, which allows for lower tire pressure. Lowering tire pressure can increase overall system efficiency, reduce rider fatigue, and offers better handling in rough conditions.  (add tire to rim transition image for hookless rims) View the Zipp tire pressure guide here.