You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
PCD is Pitch Circle Diameter. It tells you how the lug studs are positioned. You can only put wheels on a car they have the same PCD otherwise you won’t be able to get the lug studs through the holes on the wheel. Since the S and X have a different PCD than the 3 you can’t swap wheels between them.