PICKING-OUT-YOUR-NEW-SET-OF-WHEELS 101
To figure out what rim will work with your vehicle, you need to find out THREE specifications that your car uses in its factory (stock) form.
1. Most importantly, the BOLT PATTERN (5x114.3mm, 5x4.75", 6x139.7mm, etc etc). The first number in the bolt pattern is the number of lugs and the second number is the Pitch Circle Diameter. Contrary to what a lot of people say (especially when they are trying to sell you their wheels), there are NO Universal 5-lug (or 4-lug or 6-lug) wheel. A wheel is manufactured to be compatible with at most TWO bolt patterns (in a lot of cases, only ONE).
2. Secondly, the less understood spec.....OFFSET. Most cars these days are positive offset so I'll deal with that one for now. By definition, the offset is "how far the mating surface of the wheel hub is from the dead center of the wheel" (ie If a wheel is 8" wide then this dead center is at 4"). To put it more simply, a higher offset will make the wheel "go in" into the vehicle chassis more when mounted. A lower and lower offset will make a wheel stick out more and more past the fender. Also, unlike the bolt pattern (your car will accept only ONE single bolt pattern), your vehicle accepts a range of offset values (albeit narrow).
Just because your stock offset value is 46mm doesn't mean you HAVE to stick to 46mm. In this case, probably anything from 35-50mm will work depending on what you want done with your ride stance and how the suspension is set up.
3. Thirdly, WHEEL WIDTH. Going larger than stock width gives you a host of pros and cons. Most importantly you have to make sure the inner lip of the rim isn't obstructed by a control arm or something when mounted. Once that's satisfied, you can mount wider-than-stock tires on your new shiny wider-than-stock rims! That can be a great thing, for cornering and tracking stability. However if you're unwilling to do the research (or simply don't care), I'd say not go beyond your stock wheel width by more than an 1.5" just to play it safe.
This post deals with clearing up some basic wheel/rim questions. I've left tires untouched, as that deserves another (perhaps more extensive) article. But I'll say this, when selecting tires, the most major concern is to keep the overall diameter (of the tire/wheel combo) as close as you can to the stock diameter. Pls understand that I'm really generalizing here, and this article is intended to be a primer for the layman. You can really stray from the diameter (or anything else really) a large amount if you know what you're doing, or have a goal in mind. But for the average guy who's not racing and rebuilding cars, stock (close to anyway) is usually the way to go.
Thanks for reading, and feel free to contact me with questions.
To find out what your specs are, just google the year/make/model of your car (like 1997 Ford Taurus bolt pattern) and google will tell you anything and everything you need to know.