For those who are not racing their cars, alloy wheels are mainly a cosmetic difference. Alloy wheels are lighter, more fuel efficient and, in many cases, can be stronger than steel. If the added racing performance is needed, tracking, cornering and acceleration will improve.
However, with that being said, alloy wheels are nore expensive and can be a bit costlier to maintain. You have to be careful with mounting/dismounting and certain knuckle-dragging mechanics with air-wrenchs who could mess them up.
"One of the biggest differences between alloy and steel wheels is the weight. The weight of steel is heavier than alloy's aluminum, generally resulting in a lighter wheel. Less weight in turn has a performance benefit because the car, particularly the suspension, has less weight to lug around. Alloy wheels generally make a car more agile, better handling and more fuel efficient. This is why performance cars almost always have alloy wheels. It should be noted that not all alloys are lighter than steel wheels. If for instance you have a small steel wheel that is 14 inches in diameter, an alloy wheel that is 19 or 20 inches in diameter may weigh more. There is also a wide variation in the weight of alloys."
"Alloy car wheels are made from aluminum or aluminum mixed with another metal like magnesium. Alloy wheels are manufactured in a way that promotes strength, one of the reasons they are popular for race cars. Steel wheels are made of a stamped center that is generally welded to the outer rim. Alloy wheels are also less prone to bending over pot holes than steel wheels."
"Alloy dissipates heat better than steel, so cars with alloy wheels may see a slight braking improvement, since there is less heat near the brakes. There is also less chance of an wheel cracking. One advantage of steel wheels is that they are not as porous as alloys, which can very occasionally experience leaks through the porous alloy. The porosity is a result of the casting process used to make alloys. Alloys typically have an open spoke design that lets more air in to cool the brakes, though some steel wheels also have an open design. Because steel wheels retain heat more than alloys, a tire mounted on a steel wheel is more likely to have blowout. It should be noted though that steel wheels are not inherently dangerous and are widely used."
"Though there is a decent selection of steel wheels in different designs available, there are many more choices when it comes to alloy wheels. There are many companies that specialize in producing a wide range of light, high quality alloy wheels. There is also a larger choice of different sizes with alloy wheels."
"Generally speaking, alloy wheels are better looking than steel wheels. Alloys have a variety of finishes, including polished, chromed and painted. They also come in one-piece designs or multi-piece designs. Stamped steel wheels are generally much more plain looking and are either chromed or painted. However, steel wheels are popular among classic car enthusiasts for their vintage appearance."
"Here is where steel wheels have a big advantage over alloys. Because they're made from less exotic materials and are subject to less complicated manufacturing processes, steel wheels are much cheaper than alloys. A new set of steel wheels is usually $200 to $300, whereas alloys can run into the many thousands of dollars, depending on the size and brand."