Help with weird Vehicle physics asset issue

I starter doing some vehicles and did a lot of research and tutorial watching.
And as Im no novice at skinning and rigging characters I decided to rig a buggy to the an edit of the original advanced vehicle skeleton and its workd perfectly.
So I created some new skeletons for an apc I have and when setting up the physics asset i Am getting a strange issue where once I set the wheel collisions as kinematic and hit simulate the wheels shrink.!!!
I have tried creating new skeletons and re-skinning and all sorts but each time I get the same problem.
Vehicle wheels normal size.

after I set kinematic and simulate both on convex and sphere collisions.

PS i freeze transforms on all bones and mesh prior to skinning.

Imported the mesh in another project and set it up without that issue, So seems the issue is possibly related to my import settings on the main project. Import scale 1 might have fixed it… hope this is real and helps anyone else that has this issue

Ok It fixed the wheels from shrinking. But For some reason after setting up my apc with all the wheels corectly rotating and steering My apc is stuck is either stuck in the air and wont fall to the ground even though it is simulating physics and is a child of the advanced vehicle Bp. if I change the Physics asset All it can get it to to is fall to the ground but the wheels go through it and it wont move : ( just sits on the hull collision.
Why is this so weird to get working