Evasion and Pursuit
In round-by-round movement, when simply counting off squares, it’s impossible for a slow character to get away from a fast character without mitigating circumstances. Likewise, it’s easy for a fast character to get away from a slower one.
When the speeds of the two characters are equal, there are a few simple ways to resolve a chase. If one creature is pursuing another—both are moving at the same speed—and the chase continues for at least a few rounds, the characters can attempt opposed Dexterity checks to see who is the faster individual over those rounds. If the creature being chased wins, it escapes. If the pursuer wins, it catches the fleeing creature.
Sometimes a chase occurs overland and could last all day, with the two sides only occasionally getting glimpses of each other at a distance. In the event of a long chase, all parties can attempt opposed Constitution checks to determine which one can maintain the pace the longest. If the creature being chased rolls the highest, it gets away. If not, the pursuer runs down its prey, outlasting it through superior stamina.
Vehicle chases follow their own rules; see Vehicle Chases starting on page 282.
Source
Core Rulebook pg. 258