This paper studies the problem of formation control of autonomous ground vehicles (AGVs) in spite of tire sliding effects. The path tracking models of AGVs are converted into nonlinear systems via chain form transformation. An adaptive observer is designed to estimate the unknown sideslip angle for each vehicle, and distributed adaptive backstepping-based formation control strategies are proposed which guarantee that all the vehicles follow desired geometric patterns given only relative measurement information from their neighbors. Finally, the effectiveness of the proposed approach is verified by simulation examples.