The dynamics of rail vehicles during curve entry and exit, in negotiating crossovers, and in response to irregularities in the curves is of practical interest. A theory for the rail vehicle behavior in these situations is described. This theory provides for nonlinear wheel-rail geometry, large wheel-rail contact angles, and nonlinear creep forces. The application of the theory to examine the influence of the primary suspension and the wheel profiles on curving performance is discussed. This application illustrates that the dynamic behavior may dominate the steady state curving behavior, that higher conicity, “worn” wheel profiles may have superior dynamic performance, and that the dynamic performance of trucks with direct wheelset interconnections may have better dynamic curving behavior than equivalent conventional trucks.