245/45-17 tires are a very common size of low profile tires. Low profile tires are a type of tire that are characterized by their small distance between the outer edge of the wheel and the tread(the part of the tire that touches the road). To put it another way, the sidewall isn't very tall on low profile tires. This gives the car a very distinct look that a lot of people go for. Some of the cars which I have seen on the road with this size of tires are Ford Mustangs from the nineteen sixties as well as other muscle cars from this era. You may also see low profile tires on some Cadillac Escalades. However, these are almost always a size other than 245/45-17 tires. There are definitely other sizes of low profile tire other than this size. Low profile tires, such as 245 45 17 tires, as well as a distinct look, offer several different advantages as well as disadvantages when it comes to the way a car drives and handles as well.
The first major advantage I would like to mention about low profile tires is that the car almost always handles significantly better when it has low profile tires on as opposed to tires with a average aspect ratio. This is the primary reason that you see so many fast cars using tires in this size range. Many of the "European Super Cars" such as Lamborghinis and Ferraris use tires in this size range, though some models use tires with a smaller or higher aspect ratio. Other things that are usually reported by people driving cars with 245/45-17 tires is that the steering is a lot smoother. These tires can handle much sharper turns and just gives you a feeling that the steering is responding significantly better.
Improved handling and performance can come at a price however. The main disadvantage of low profile tires is that there is so much less cushioning than there are with other sizes of tire. This really shouldn't come as much of a surprise when you consider that the sidewall is half the size of some other tires. Every bump and imperfection on the road will go strait to the suspension on your car rather than a large portion of it being absorbed by the tires themselves. This means that the driver and passengers will experience every bump that much more than they normally would. This really isn't as bad as it sounds however. You need to remember that cars which use tires with more sidewall are the ones which you take off road. You will never see someone taking a Lamborghini onto a road that is really in that bad of shape, and if you do, that driver and passengers will have a lot of problems other than just experiencing a few more bumps that usual.
So, 245/45-17 tires have a shorter distance between the wheel and the road which gives you smoother and more responsive steering but will give you a ride that is much less smooth when the road is in poor quality.