A simulating method for vehicle/tire performances which includes: a tire model preparing step (s1) of preparing a tire model of a tire including a ply made out of a finite number of elements; a vehicle body model preparing step (s2) of preparing a vehicle body model of a vehicle body including suspension members made out of a finite number of elements; a vehicle model preparing step (s3) of preparing a vehicle model by attaching the tire model to a suspension model of the suspension members in the vehicle body model; and a simulation step (s4, s5) of virtually running the vehicle model by giving a boundary condition, and estimating vehicle's traveling properties and/or a tire property.