Chaining matrices correctly

Hello! I have a mars rover. The body is one mesh, and the 6 wheels are another. The body moves correctly, with translation and rotation matrices, but when I try and add the wheels things go a bit weird. Each wheel has coords which define the displacement from the centre of the rover. That works fine : D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &wheelPos ); D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &roverWorld ); When I try to get the wheels to turn as the rover moves, they do all sorts of weirdness, wobbling around and turning sideways etc! I use : D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &wheelRot ); D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &wheelPos ); D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &roverWorld ); I've tried: D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &wheelRot ); D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &wheelPos ); D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &roverRot ); D3DXMatrixMultiply( &wheelWorld, &wheelWorld, &roverPos ); But this is still bad! Any suggestions thanks!!! Simon