Keep one thing in mind, if you are going to switch tire or wheel sizes. Going from a 16" to a 17' size (or vice-versa) could in some cases affect the speedometer, odometer, and other speed and wheel-RPM-related functions. What matters most is the outside circumference of the tire-wheel assembly....conversion charts are available to match tire-wheel assemblies and maintain the same outside wheel/tire diameter and circumference that the sensors that were put on the car at the factory are designed for.
If you decide to go to an aftermarket wheel, make sure, of course, that not only the bolt pattern is compatible, but that the design of the wheel doesn't block airflow to the brake rotors for cooling.

 

I'm sorry, but I am clueless. What do you mean? Do I have to change the wheels to get new tires?

Right now, there is a set of Nankang 215/45/17 tires on the car. Does this mean my wheels are only set for 17" tires?

Again, how does one decide whether to put 16" or 17" tires?

 

The last number of your tire size indicates what size rim/wheel the tire fits. You have indicated by your tire size that you have 17 inch wheels therefore you need 17 inch tires.

 

Some IS300 owners chose a 16 inch all season wheel and tire option for improved performance during bad weather (and a softer ride as well due to taller side wall). See tirerack.com or tires.com for more info on wheel and tire sizing options.

 

It's definitely okay to put on 17's but be aware of the huge price differences with summer only tires and "all season performance".

 

First of all, thank you all for replying to my newbie messages.

So, since I have 17" wheels, I looked at Tirerack.com and narrowed my choices to these two all-season tires:

Continental ContiExtremeContact, Size:215/45-17, WR Speed Rated
Pirelli PZero Nero M&S, Size:215/45-17, WR Speed Rated

Would anyone with experiences with these tire care to comment on whether the survey results found on Tirerack.com are consistent with his experiences?

http://www.tirerack.com/tires/tires....omCompare1=yes

http://www.tirerack.com/tires/tires....omCompare1=yes

Also, Consumer Reports seems to think highly of Falken Ziex ZE 512 tires and Bridgestone Turanza LS-H tires. Any experiences with these anyone?