The first thing is to work out what size wheels you want to fit, then that will dictate what size tyres you would need.
Then check out what tyres are available in that size and how much they cost. For instance, a 195/45x16 tyre would be equivalent to your 175/65x14 but they're not a common size so they will not be particularly cheap, like a 205/40x17 for example.
If you're happy/don't care/own a tyre factory then find wheels with a 4x98 or 4x100PCD (you will need special bolts - aka "wobble bolts" - for the latter) and a 58.1 centre bore.
A larger bore (e.g. 65mm) can be sleeved down with a spigot ring. You *need* spigot rings if your wheel bore is bigger than 58.1mm.. since they support the weight of the car on the wheel. The bolts are just there to hold the wheel to the hub.
Offset is less crucial. If the wheel (i.e. not the tyre) is 1" (25.4mm) wider then you ought to increase the offset by 5 or 6 mm to stop it sticking out half an inch, just through being wider (if it had the same offset).
Too-wide wheels a) look stoopid - yes they do - and b) will foul on your wheel arch liners at full lock. It's not a good look when your tyre rips out the liner. I'm not a fan of spacers.. so ideally find a wider wheel and offset combination so you don't need spacers.
The main thing after you got the wheel that fits is to match the new tyre to give the same sort of rolling radius/diameter as the old one. Don't fit balloon tyres with too high sidewalls (see "Too wide wheels").
Also make sure that the wider tyre you will inevitably fit does not foul the suspension or the wheel arches. If you have a larger, wider wheel with the same or slightly greater offset and fit a tyre that matches the rolling radius/diameter of the old one, then you'll very certainly be okay.
Ralf S.