Check the tyre guide on the drivers side door panel. It should show all the sizes that come on the model you have. It seems like you have narrow wides, which indicates a possible M Sport model. Most probably you have the correct tyres on.
These cars are designed to have a heavy steering as it gives good front wheel feedback.
Also make sure you have the right tyre pressures and the tyres are not worn. Worn tyres have more contact with the road causing heavy steering.