The main objective of this paper is to evaluate the performance of the flexible pavement under
different conditions of axle loads and tire pressure of different vehicles (trucks) in Egypt.. Strains
of different pavement sections were calculated using computer program based on linear elastic
theory. Moreover, theoretical analysis was achieved by using BISAR computer program to obtain
regression equations to simplify determination of load equivalency factor (LEF) as a function of
axle loads and tire pressure for single and tandem axle loads. A comparison between the values of
calculated LEF and these that adopted by the AASHTO specifications was achieved . From the
results analysis, it could be obtained that , at low to intermediate axle loads, high tire pressure
could cause marked increase in LEF. At high axle loads, variation of equivalency factor with tire
pressure could be neglected. Moreover, increased subgrade elastic modulus had insignificant
influence on LEF