hey i'm new to the forum and i could have sworn i tried to post this before but it didn't go up or something, but anyways i am trying to find out the smallest diameter rim that will fit the xf. i have 20" chrome rims for daily driving and i've been using the stockers for racing but even the stock wheels are retarded heavy. so in order to try and reduce some un spun weight i'm trying to find out what the smallest rim i can get is... anyone know? i'm thinking 17's would clear but i don't want to find out the hard way lol. thanks for your help.

 

17's might fit, but unless someone has had the exact wheel you're interested on the car, you wouldn't know...2 wheels with the same diameter/width/offset can still have different spoke and inner shell shapes...one might clear and the other not.

A reasonably cheap and light option I can guarantee will work are the Enkei RS7's in 18x7.5...about 19.5 lbs and $149 each here:
http://www.wheelcomponents.com/enkei.html

Perfect for the front, but the offset/width would be a little funky for the rear.

I've got 19x9, 23 lb Konig Next's for the rear, but I'm not sure they're making them any more...I think I have the last 4 that discount tire had (and got them for $50/wheel)!

 

23 lbs isn't bad. its just so hard to find a good staggered fitment. i think i'm gonna go down to the porsche shop again and see what they can get me or at least recommend. they deal with that stuff all the time. thanks.

 

http://www.acealloywheel.com/
http://www.milanomotoring.com/wheels.htm

Stick with 18's F&R IMHO.

 

IRWIN, I don't know what kind of racing you are doing, but for drag racing, I'm sure a smaller diameter wheel would improve your ET's.
Just for the record, Motor Trend's Dec 2003 issue had a comparison road test of the Crossfire and the '03 Mercedes SLK. Both cars were automatics, and mechanically identical. Even though the SLK weighed 70 lbs. more, it still ran the 1/4 mile in 14.84 sec. vs the Crossfires 15.18. The only reason given for the better performance was the smaller wheels and tires, and less unsprung weight.
The diameter of the SLK's rear tire had to be the same as the Crossfires because they were both turning 2,250 RPM's at 60 mph.
The SLK had 205/55-16's in the front, and 225/50-16's in the rear.
Both cars use the same brake and hub assemblies so the SLK's wheels should go right on a Crossfire.
Even with these much smaller wheel and tires, the SLK still had a .03 wider front and rear "track" than the Crossfire too.
It probably goes without saying, the Crossfire ran a much better slalom than the SLK, 66.0 mph vs 62.8, and pulled a 0.87 vs 0.81 on the skidpad thanks to it's much larger tires.

 

yeah i think the 18" enkeis if i can find them in the right offset... to be honest my 20" chrome wheels aren't that much heavier than the stockers which say something about the strength of those wheels but like you said a car with the same drive train only 70 lbs heavier... wheels makes a big difference and i don't believe it necessary now to have the 10 inch wide tires in the rear now since the 20's are 8.5 and on straight line i can't really burn them. the stock tires though imo are trash i'm coming up on the wear bars with 7k miles on them that's bs no matter what. so the lightest 18's and the stickiest rubber it shall be.