Our ‘08 had AD and it is transformative in terms of handling. Made it a great for towing as well.


Sent from my iPhone using Tapatalk Pro

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'

;)

In some aspects, 20s will not perform better than the 19s because of weight but not in terms of stopping feet and skidpad tests (below). Stopping feet is an every day driving occurrence and so is handling (skidpad more related to higher speeds).

Car and Driver:

X5 non-20s:
Braking, 70-0 mph: 169 ft
Roadholding, 200-ft-dia skidpad: 0.82-g

X5 20s:
Braking, 70-0 mph: 159 ft
Roadholding, 200-ft-dia skidpad:: 0.87-g

You've got a link perhaps?

Same precise car, only change is rim size- same model tire too?

Sure, here they are (one is an '07 4.8 non-20s and other is '10 35i with 20s and Adaptive):

https://www.caranddriver.com/reviews...e35i-road-test

https://www.caranddriver.com/reviews...take-road-test

Love the AD and handling!!!

Hate the curb rash 20's when parking Wash DC

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.

Same exact tire model, just different sidewalls?

you are posting testing of two different cars

This is NOT a test of 20s versus non-20s.

In my case, considerably different tire width and rim width as well as rim diameter. But same brand of tires. The car came with 19s, and I bought the 20s a few months after I got the car. Now I use the 19s for snow tires, so I still switch back and forth; but it's not as much of a comparison as when I had all season DSWs on the 19s as I have on the 20s.