Just to begin with:
When you attach one object to another.
For example, you have a spaceship and you want to attach a wing. Or you have a truck and you want to attach a container on the back. Or you have a player character and you want to attach a backpack.
Simply - you need to use the parent-child relationship
Note that the parent goes with the “transform”.
So in short, you would do something like this:
One – make a new “wheel unit”. Use “Instantiate” to do this. if you do not know about Instantiate read the doco, or ask a new question, or search.
newWheelUnit = Instantiate( myModelWheenUnit );
You now have a beautiful new wheel unit.
So. Now you must make it that your VEHICLE is the PARENT of that new wheel unit. Don’t forget, you have to use “transform” for this.
So first set all the other stuff for newWheelUnit …
newWheelUnit.name = "special name";
newWheelUnit.layer = 13;
Now set the parent …
newWheelUnity.transform.parent = yourCar.transform;
Now you have to set the position of that child. USe localPosition to do that.
newWheelUnity.transform.localPosition = Vector3(0,0,0);
it won’t actually be “0,0,0” 0 it will be the actual position of the wheel on the car. Since it works in meters, it might be something like “1.25, -0.835, 0”
First you have to master all this so that you can easily “add parts” to something else
Once you get really good at this, you have to look in to the whole topic of making wheels turn, etc. That is a hugely separate topic and you will need to do a lot of searching and questioning. Good luck!