First thing you need to do is learn the basics of Rims (Fælge) , Tires (Dæk) and the Combination result of a wheel (hjul).
The 4 rims and 4 tires on a vehicle MUST be identical in dimænsjens..
You can easily find a rim that you can mount, because to mount only requires the correct Bolt / Lug number and pattern / mæsjerment..
BUT BE SERIOUS.. ONLY MOUNT 4 IDENTICAL DIMÆNSJEN RIMS...
Take my family car as an examp., a Fiat Panda III from 2012...
It uses a HjulNav structure (Wheel Flange) with 4 Bolts in a 98mm Circle Diameter, with a center hole of 58,1mm and can variate from 32 to 38mm in Offset / backspacing, ET (Einpress Tiefe)..
Those MUST BE FOLLOWED..
What you can choose within is usually 14, 15 or 16 inch rims, or on bigger cars, likewise, 17, 18 or 19 inch..
What you must to is look up the technical info on YOUR CAR.
INSTRUKTION MANUAL, ONLINE Wheel merchants info tables where you write in your license plate or Car Model exactly and get info onscreen.
Also, very important to unmount your wheels and look on them. It can be either on the front or back, there will be the dimensions in this code ,,, 6J15H2 F498 ET35... NUMBERS WILL BE DIFFERENT ON DIFFERENT CARS...
6J means a 6 inch WIDE rim with a J architecture...
15 is the rim diameter again in inches.
H2 is also rim architecture, don't worry about that but keep all 4 rims in same architecture profile.. They will be automatically in 99pct cases.
F4 is a code used for 4 bolt setups in Fiat and other brands' models.
ET35 is again the backspace. The length from the CENTER OF THE WIDTH OF THE RIM TILL THE CONTACT FLANGE, HJULNAVVET, WHERE THE RIM MEETS THE CAR.
In 195/60R15 the 60 is NOT the percentage OF THE SIDEWALL HEIGHT.
It is THE PERCENTAGE OF THE TIRES WIDTH WHIIIIICH EQUALS THE DIMENSION OF THE SIDEWALL Height.
If you drove on 195/100 tires they would be 195mm wide and have sidewalls of 195mm height.
Now, only use your spare rims with the present rims once you've correctly checked all this to be equal measures and once you inspected that it has no structural damage or even minor damage to the area where the tire bead will settle and make the airtight seal..
Try to purchase Aluminium rims with a professional lacquer finish. The smooth lacquer is very important, the COLOR is NOT.
Get ALL info on rims before you send money to the seller . Best to see it in reality first..
Steel rims will rust out from within, slowly destroying its own ability to hold the airtight seal. The water on them will soak up rust and that may spread to other places in the break and suspension system..
I personally sprayed my almost new Steel rims for the Panda with quality Zink paint and still they could not hold back the iron in the steel from rusting out thru BOTH the original black lacquer paint on the steel AND the Zink layer..