This paper presents the results of full scale vehicle testing completed to examine deceleration factors, or friction coefficients, on various off-road and on-road surfaces. Of particular interest is the relationship between vehicle side slip and deceleration rates on soft, off-road, deformable soils. Vehicle testing was conducted at slip angles of 0, 30, 45, 60, and 90 degrees with locked and unlocked wheels. A comparison of the experimental data is made with respect to the theoretical prediction of deceleration being trigonometrically related to slip angle. Results indicate the theoretical prediction as fairly approximate through a portion of the side slip range. As side slip angles approach 90 degrees, actual measured values are higher than predicted.