Rolling Wheel as a character : dealing with rotations

Hey everyone !
I'm very new to unity and programming, and I'm trying to create a controller for a wheel character (you litterally play a loose wheel rolling), for which I want to use rigidbody. Since the wheel is constantly rotating, I used another object (that copies the wheel's position) that controls its y rotation (turning left/right) and where "forward" is (since its z axis is constantly turning). It works pretty well, except from the fact that the wheel stops rotating on the X axis when it reaches 90 or -90 rotation, I spent a lot of time trying things, but I couldn't do it on my own. Here is what I have so far (in case this is isn't clear, the RotationTarget is an empty that copies the Character's position, and whose Yrotation is instructed by the keyboard) :

Code (CSharp):

1.  public class CharacterMovement : MonoBehaviour
2.      {
3.    
4.      
5.          private Rigidbody rb;
6.    
7.          public GameObject RotationTarget;
8.    
9.          private Transform TargetTransform;
10.      
11.    
12.    
13.    
14.          void Start ()
15.    
16.          {
17.              rb = GetComponent<Rigidbody>();
18.            
19.          }
20.      
21.    
22.          void Update()
23.          {
24.      
25.            
26.              float vertical = Input.GetAxis("Vertical");
27.            
28.          
29.              // Getting the wheel to roll, works pretty well
30.              TargetTransform = RotationTarget.GetComponent<Transform>();
31.              rb.velocity += vertical*TargetTransform.forward * Time.deltaTime*10;
32. // Getting the wheel to rotate on Y and Z as the Target but on X as it should as a rigidbody)
33.              transform.rotation = Quaternion.Euler (transform.eulerAngles.x, TargetTransform.eulerAngles.y, TargetTransform.eulerAngles.z);
34.        
35.    
36.    
37.          }

I may have gotten this completely wrong (for example I add force to the rigidbody's velocity, whereas it may have made more sense to add force to its rotation/angular velocity ? It looks good this way so I have left it as is so far), if you have a better solution I'd love to hear it

Thanks a lot

 

instead of coding the wheel to rotate you can create a animation of the wheel rotation then have the parent of that object be the movement controller