Wheel offsets

[Oilcan]

Hello All, I am a new audi owner and new to the Club, so please be gentle.

I am the proud owner of a A3 2.0 tdi s line black ed in ibis white with gunmetal 18s.

 

I live in the North of Scotland and am getting ready for winter. I have a set of 225/40 18 Toyo winter tyres but need a spare set of wheels. I have been looking at the gunmetal rotor styles on the popular online auction site but there are varying offsets from 30 to 45  with a lot saying they

will not fit my car. Any one know the correct offsets? Ps I have checked the pcd..5x112