17" rims

[rocco16 at sbcglobal.net (LEF)]

  Larger, wider wheels combined with lower profile rubber allow significantly greater grip in the corners. 

  While I certainly agree that lower profile rubber aids performance, it's not necessary to go to overly large diameter wheels in order to find the requisite rubber.  You can purchase very high performance (DOT-race, actually) down to 35-series in 15" tires, for example.  
  I also agree that wider wheels are also very desireable from a performance standpoint, but again, you can find wheels in virtually any width you want in 13", 14", 15", etc.......so 17" wheels are not required to get this benefit either.

  I've found that the larger diameter, lower profile tires deflect less for a given weight and lateral loading. 

  I'm not sure how one comes to this conclusion since tire profile has everything to do with sidewall deflection, and tire (rim) diameter has virtually nothing.    In fact, the larger diameter wheel (itself) will deflect more for a given loading than will a smaller diameter wheel, all else being equal.



    Getting that contact patch to shift from narrow to wide sometimes means moving to a larger diameter wheel, since the desired aspect and width is just not available in the smaller diameter.  

  Wheel/tire diameter actually has little effect on contact patch width, other than a larger overall diameter will lengthen the patch, which is not desireable.  Again,  wide wheel widths, along with low aspect tires, ARE available in the smaller tires such as the 15".



   That is tantamount to saying that any lister with stock brakes should still be running stock wheels and tires, or 14x9's.

  While stock wheel widths are not 9"....(be nice if they were)... yes, that is exactly what I am saying.  The most efficient use of brakes will come when you use the smallest diameter tire/wheel combo that will clear the hardware. 
    
   they could have stepped down from a 20" for the added unsprung weight savings alone, but they did not - because there really is more to wheel diameter choice than brake clearance.

  Indeed there is; it's commonly known as "marketing".  :)    Not everyone who buys an exotic is clued in on wheels/tires.  In fact, I'd say the average Scirocco lister probably knows more than the average exotic purchaser.

  You bring up a good point I had forgotten: unsprung and rotating weight.  From what I read, the smaller the wheel diameter, generally, the less the whole assembly will weigh.  (I get that information from other sources, since I've not had the resources to purchase and weigh the necessary samplings of various  diameter/material/design/widths stock and aftermarket wheels and the myriad tires that could be matched up.)
  My $.02, as well.  :)
  larry
  sandiego16v


  My $0.02
  Al