Quote:
Originally Posted by ard
Agree that AD is transformative.
20" rims will REDUCE performance. The constant drumbeat of low profile=performance is driven by industry dollars and then in turn market demand.
To the consternation of designers, they are being forced by marketing to put on lower profile tires - to the detriment of handling.
And remember, what numbers you get on a perfectly smoot skid pad will be only a component- you really want is real-life, street/road performance numbers. And not 'how if feels'

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A lot depends on the type of performance you are measuring. AutoX? Racetrack? Skidpad? Slalom? or Real world?
I can tell you that my sport package X5 w/adaptive drive corners very flat, and stable; regardless of 19" vs 20" wheels. Since I don't plan on autocrossing or tracking my X5 anytime soon, that leaves REAL WORLD driving. I can tell you from the fact that I've actually tried BOTH 19" and 20" wheels on my X5, that the 20's make a huge improvement in high speed stability and high speed comfort; I'm talking in excess of 80mph here. There's a big difference in terms of resistance to wind gusts, and road irregularities. This IS a factor due to the large boxy shape of the X5. I'm not sure if it's the lower sidewall height or the added tire width, but there is a VERY noticeable difference in how the car FEELS. It's absolutely NOT just hype, and I do understand the importance of unsprung weight; and lower vehicle weight in general. With the 20's, you can basically drive as fast as you want and feel totally relaxed. With the 19's, anything over 80mph and you need to be much more focused due to the requirement of more tiny directional corrections.