Tips on Buying Cars: Wheels, wheel diameter, wheels and tires

Question
What is the difference between a car with 14 inch wheels and 15 inch wheels? I know that the 15 inch covers more ground so it generally has higher fuel efficiency, but is it worth it in the long run compared to how much more it costs to install 15 inch wheels? Also, alloy wheels have better handling than steel wheels, but is it worth the price? Is the difference significant? Just in case it matters, I don't have much driving experience but I plan to go on road trips after I get my first car.

Answer
The wheel diameter is only one part of the equation.  What really matters is the overall diameter of the tire that is mounted on the wheel.  The most important thing to remember is that with today's computer controlled vehicles, maintaining an overall size that is equal to the original size is very important.  It affects your speedometer, transmission shift points and ABS.  If you have 14" wheels and go to 15", then you'll compensate with a shorter tire.  The taller the wheel, the shorter the tire.  The shorter the tire, the better a vehicle handles as less flexing occurs in the sidewall.  Without that flex though, the vehicle also rides rougher and sends more shock through the suspension system.  
The wheel material alone, ie. steel vs. aluminum has nothing to do with handling.

One big mistake that young drivers make is to put expensive wheels and tires on a car at an age where they are most likely (no offense) to be hitting curbs and stuff.  Keep it simple and original.  Spend that money on taking care of the car and getting it paid for.

Clear as mud?