2d wheels sink into ground because the circle colliders change size on flip?

Hi All,
New to this, and have spent a few days getting something i'm pretty pleased with when it's moving right: when my wheeled vehicle moves left it sinks into the surface below.

I've done a few searches and know that there have been problems in the past with colliders stopping working when you flip a sprite to ( theScale.x *= -1 ) in 2D mode.

A few quick pauses reveals that although the Circle Collider seems happy enough according to the numbers in the inspector, visually the circle representing it shrinks to a random size whenever I scale to -1. It returns to the correct size when I scale back to +1 and my vehicle moves on just fine.

I've uploaded a screenshot (the scale happens in the parent object, and note that the wheels are actually sitting in the right place for the ground collider - it just doesn't happen to fit the graphic yet) - there's a lot of pale green in it but hopefully you can make out what i'm getting at.

Thanks PaulxT

 

Question to self - does the resize relate to the rotation? [I'll check later]

Further info - the flip function looks like this at the moment - the problem exists without the foreach loops at the bottom - I was trying those based on some advice found nearby these parts, but which was dated from previous versions.

voidflip()
{
//theSkull.MovePosition (Vector2.up * 300);
theSkull.AddForce (Vector2.up * 200);
//Switchthewaytheplayerislabelledasfacing
facingRight = facingRight*-1;
//Multiplytheplayer'sxlocalscaleby -1
Vector3theScale = transform.localScale;
theScale.x *= -1;
transform.localScale = theScale;
//forceallchildcolliderstoupdatetheirpositionbyenabling/disablingthem

foreach(Collider2DcollideringameObject.GetComponents<Collider2D>()) {
collider.enabled=false;
collider.enabled=true;
Debug.Log (collider.name);
}
foreach(Collider2DcollideringameObject.GetComponentsInChildren<Collider2D>()) {
collider.enabled=false;
collider.enabled=true;
Debug.Log (collider.name);
}
}

 

Ok - i've no idea why the wheel colliders were resizing, so I took a different approach and rotated 180 on the y axis. This left the wheels where they were, and they were stuck where they were because of the hinges they were attached to had anchor co-ordinates that was forcing them to be in a particular place? Bit confusing to me, and took a bit of thinking, and now my flip code looks like this:

theHinges = GetComponents<HingeJoint2D>();

void flip()
{
facingRight = facingRight*-1;
for(inti = 0; i < theHinges.Length; i++)
{
Vector2hingeLoc = theHinges.anchor;
hingeLoc.x=-hingeLoc.x;
theHinges.anchor=hingeLoc;
}
if (facingRight<0)
{
transform.localRotation = Quaternion.Euler(0, 180f, 0);
}
else
{
transform.localRotation = Quaternion.Euler(0, 0, 0);
}
}

Which works just fine - hope this helps someone at some point down the line