There's also the center bore of the wheel to consider, it should fit nicely over the hub of the car to keep the wheel centered while tightening the lug nuts.
Yes, make sure you know whether the car is Hub-centric or Lug-centric. If it's hub centric you'll need the same size bore in the center of the wheel. This can sometimes be changed on aftermarket rims by using different size hub rings made from alumnim or plastic.