In order to shorten the travel time of limited express trains operated between Sapporo and Kusiro in Japan, a tilting diesel car called series DC283 (passenger car for a limited express train) with forced steering bogies (DC283 forced steering bogies) has been developed by JR Hokkaido and RTRI. This paper describes the lateral force between wheel and rail observed with this test car on curve and that obtained from coresponding computer simulations. The results of simulations and field tests are as follows. (1) DC283 forced steering bogie can reduce the lateral force between wheel and rail. (2) The decrease of the lateral force due to the forced steering bogie should be verified not only on circular curves but also on transition curves. (3) The lateral force of the first wheelset is the largest. (4) To decrease the lateral force more effectively, the steering ratio is set 35 percent (Lv=1.35) higher than the value that makes the radial position. (5) The running stability at the maximum speed of 140km/h is satisfactory in field tests.