I have been considering alloy wheels for my T25 1.9 Petrol Camper, Manual 1983 and have come to the conclusion that I would like steel wheels instead so that I won't worry about scuffing them
I would like 15" as I currently have 14". I would consider 16" but I want to improve the road holding a little but not make her too sensitive for the bumps when it comes to a little off-roading

What size wheels and tyre combinations can I source? 15" x 5.5" etc (I have never tried to understand that part of the sizing) and the width and profile of the tyres - someone once told me you have a 10mm range, e.g. 195/50/15 or 205/50/15 can fit the same wheel?
Also, can I take them off certain vehicles? For example, can I put old Passat wheels on? Someone once mentioned Audi wheels to me. I believe for quite a few years cars have come with 15" steel so I am hoping I can find someone who wants to upgrade to alloys and sell theirs. I am not a novice with tyres and wheels but I am not confident enough to make sure I don't affect the speedo or end up with wheels that rub. I understand that alloys often need spacers but steel wouldn't?
I tried Eurovans as my first point of contact but the steel wheels are no longer listed.
Sorry for the ramble and thank you in advance for looking and hopefully assisting me with this issue. My tyres are quite old (a pair are 8 years old if I remember correctly) and I would like to replace them but there's no point if I want to get bigger wheels...I understand no matter how much you try you can't stretch hardly used 14" tyres onto a 15" wheel!

Cheers
Stu