Many factors influence the rigid pavement's fatigue life. The most important of these factors are axle loading, the spacing between axles in the one-axle group, and the type of used tires. This study showed the influence of various rear axle spacings on the life of fatigue damage and identified the performance of the rigid pavement. The Finite Element software program DYNA-SLAB was used to calculate the stresses under the various axles. The fatigue life was assessed by the Mechanistic-Empirical Design Guide (M-EPDG) equation depending on the result of stresses from the DYNA-SLAB program, then the Axle Factor for each axle type was calculated. The results indicated that by increasing axle spacing in the one-axle group up to 2.20m for tandem and tridem axle, the Axle Factor decreased, giving the best performance of the rigid pavement. But for quad axles, if the spacing is more than 2 m, the Axle Factor increased and gives the worst performance of the rigid pavement.