As the others have said, 100pcd, 8j 225/40/18 ET48 is spot on. Offset will vary from wheel to wheel, the standard wheels are 53 I think?
You can fit 8.5j ET55 under there
but that's not 100% the correct offset I believe,
The centre should be 56.1mm, though check this to be 100% you can fit hub centric spacers to some wheels but they are not ideal really, better to get ones the correct size to start with.
Also different alloys need different wheel nuts! worth noting, Speedlines for example are totally different to standard!.. don't buy "light weight" wheel nuts.. unless they are titanium!
7.5 is a little narrow.. you should be looking at 8's really
It's also worth making sure what you go for has clearance for Brembo or AP calipers to safe guard yourself for future potential upgrades.