Force and moment measurement accuracy of the tire test rig directly affects the accuracy of the tire data. A new type of tire test rig developed by research team was analyzed. Based on multi body dynamics theory, the mechanism of the attitude control of the test rig was analyzed and equation solver of force and moment of the test rig was derived. The accuracy of equation solver was verified by abaqus which is finite element software. Then the test rig which had been designed and processed was calibrated. The results showed that forces in three directions were in good agreement with the calibration, while moments were not particularly desirable. A reasonable assumption was made that the space bias of hard point at the hinged of six power cylinder of tire test rig was existed. Then the identification and optimization of spatial coordinates were made. The results showed that the optimized forces and moments in three directions were in good agreement with the calibration. Force accuracy was higher than 0.75% and torque precision can reach about 1%. Results proved that hinged misalignment assumptions were reasonable, also indicated the potential of this new test rig on the test accuracy.