I would venture to say the current,
aftermarket, set-up I have is how the car should have come from the factory. I would love to see the skid-pad and braking performance of my car vs a stock 2009 Genesis 4.6.
I feel I can make a real world statement regarding the difference because I have twice had a 2010 loaner sedan identical in color and options as mine; however, having the obvious upgraded items like suspension, adaptive cruise control, auto-hold brake, etc..
I live 57 miles from my business and I decided to keep the loaner car for 24 hours, so I could play with the adaptive cruise and determine if I could really tell a difference with the improved suspension.
I also drive a lot. I have 32000 mile on my Genesis that I purchased 11 months ago, so I have a fair amount of "seat time"....
Getting to the point of my opening statement:
I drive aggressive. Not abusive, but aggressive. I take corners fast, entrance ramps and exit ramps quickly, etc. There are entrance ramps on my commute that I've grown to know well and also grown to know what my limits are pertaining to the handling capabilities of my car. When I drove the 2010 loaner car home and entered into a fast sweeping right hander style entrance ramp to I-95, the car pushed and scrubbed off speed a lot sooner than my 2009. All of this has nothing to do with suspension (granted, suspension is everything, as are brakes, but both are nothing without grip from tires)
I think Hyundai really fell short by putting a 7.5" wide
wheel on our cars. My 2005 Mercedes C230, weighing 3200lbs has wider wheels on it. They are only 17' wheels, but the are wider by an inch and allow for a larger foot print of tire to contact the road.
Here's what I have and what I have noticed about my ride:
18x9" TSW Vortex wheels 5x114.3 with a 35 off-set.
I'm running a very affordable 255/45/18 Bridgestone Potenza RE760 Sports at all four corners.
I originally went with an 8" wide
wheel up front but soon purchased 2 more 9" wide wheels for the front and what a difference it made in the car's stance and handling during turn-in.
I spent a lot of time determining the optimal set up (even though I now think I'm going to a 19"
wheel and possibly a loss in ride quality). I say optimal because with the 18x9 set-up I currently have I swear my car is quieter, smoother, and better handling than the 2010 I had as a loaner. The Bridgestone tires are definitely less noisy that the OEM Dunlops on the 2010.
Here's a picture just after running it through the car wash. I'll try and take some current ones that show the difference in the 8 and 9" wide wheels on the front.
Wheel link:
http://www.discounttiredirect.com/direct/wheels/tsw/product/submitProductSize.do?pc=64034&tmn=Vortex&typ=Car%2FMinivan
Tire link:
http://www.tirerack.com/tires/tires.jsp?tireMake=Bridgestone&tireModel=Potenza+RE760+Sport
I'm not saying the Bridgestone is the "best" tire, but I'm telling you, it's a "great" tire for the money. If I were to pay $100.00 more per tire for something else, I seriously doubt I would notice a 40% ride and handling improvement. Plus, I go through tires quickly and need to make sure I try to be economical about it.
In the five years that I've owned my Mercedes, I put 18 sets of rear tires (255/40/17) and 13 sets of front tires (225/45/17) I have run 4 different tires on that car. Contis, Kuhmos, Falken, and Fuzions The Falken FK452's were the worst handling and nosiest. The tire I found to be nearly identical to the OEM Conti's were the Fuzion Zr-1's. Man! What a great tire for only $105.00 each! sticky, quiet and the wore well.
Hope that helps!