This paper presents an algorithm for adapting the tire inflation pressure of off road vehicles operating on rough terrain to reach tire floatation. The algorithm accounts for dynamic effects of tire sinkage and tire deflection in the vehicle/terrain interaction. Extensive simulation and experimental results demonstrate the method effectiveness. In order to evaluate the variability of sinkage measurements using three different shapes (rectangular, ellipse and circular plates) on a uniformly prepared sand soil with three different bulk densities of 1200, 1270 and 1315 kg. m-3 and three different moisture contents, a set of three plates having dimensions of (34*85), (45*64) and (40*61.6) mm for rectangular plates, (40*97), (37*92) and (33*52) for ellipse plates, 27.5, 26.7 and 30 mm radius for circle plates were tested for pressure vs sinkage results five times each in four test series. From the individual plate sinkage vs. pressure results, the constants kc, kφ and n in Bekker's sinkage equation were evaluated using groups of three plates and a least squares best fit procedure. The instrumentation of the sinkage device and the measurements of the response of sand to normal loading in laboratory conditions are presented. The sinkage tests were conducted by means of static weight driven loading equipment. The vertical plate sinkage and the load applied to the plate were measured. From the experimental data, the sinkage parameters kc, kf and n in Bekker pressure-sinkage equation could be derived. The results showed that the used experimental device was suitable for identifying the soil sinkage parameters in relation to off-road mobility. The purpose of this study is to estimate the proper tire inflation pressure according to soil conditions. The soil conditions are varied from hard to soft as soil bulk density and soil moisture are changed the results showed that the constants kc, kφ and n are changed as soil moisture and bulk density change. The highest value for kc and kφ were found at the lower soil moisture content and bulk density. Values of exponent n ranged from 1 to 1.53 according to soil condition and sinkage plate shape. The constants in Bekker's sinkage equation derived from rectangle and ellipse shape are very closed each other than they get from the circle sinkage shape.