<p>The fire spread among vehicles in tunnels can lead to a rapid increase in temperature, resulting in catastrophic consequences. To elucidate the evolution pattern of fire spread among vehicles in tunnels, this study employed Computational Fluid Dynamics (CFD) methods for simulation research. Initially, based on vehicle fire experiments, a vehicle fire spread simulation method considering fire breaching the windows is proposed and validated. Subsequently, the credible worst case and representative fire scenario generation techniques are proposed, and the fire spread simulation method is applied to fire scenarios to investigate the evolution process of vehicle fire spread under realistic traffic conditions in tunnels. The results indicate that the proposed vehicle fire spread simulation method is accurate and effective, with the rubber ignition point serving as the critical temperature for vehicle-to-vehicle fire spread. The spread of vehicle fire exhibits a domino effect, where large vehicles are more prone to ignition, and once a large vehicle becomes a secondary fire, it triggers extensive fire spread, with tunnel temperatures reaching up to 1800&#xa0;°C. The distance between queued vehicles and initial fire, as well as the spacing between queued vehicles, affect the progress of fire spread. This study aims to provide more realistic vehicle fire spread patterns and temperature distributions for performance-based fire safety design in tunnels.</p>