Like many owners who rotate their own tires, I hate the lousy two-piece factory lug nuts that tend to fall apart if you look at them wrong that so many manufacturers (including Jaguar) tend to use these days. I believe I can purchase a set of 20 McGard one-piece chrome lug nuts (guaranteed to never rust) for about $70 through a local aftermarket shop, but the shop must see my wheels and lug nuts before they decide if these McGard lug nuts will work and be safe.

Can anyone out there confirm that my 2005 S-Type 3.0 with 17-inch Kronos wheels with 5 lugs per wheel requires a 12 mm lug nut?

 

You have the size right. I would guess the reason the shop wants to see the wheels and lug nuts is to make sure the replacements seat properly. The factory lugs use a small cone and washer. I would guess that standard conical nuts may not seat correctly. BTW: I haven't had a single issue with the lug nuts on mine and they are identical to yours. Do you apply a anti-seize to the studs? I've done that for years and haven't had a lug strip or break.

 

You're correct about the shop wanting to ensure that the McGard lug nuts will seat properly. I've bought replacement lug nuts for other vehicles before, and this is standard operating procedure for them. Obviously, they have a good lawyer and think about liability before they sell you something that may not work. More shops should do that....

I haven't had a lug nut strip or break, either. The acorn-style caps just get loose over time. I know from experience with other two-piece lug nuts that when the caps get loose, eventually they will come apart. Transitioning to a one-piece lug nut solves that problem. But cheap lug nuts will usually develop rust rather quickly. I've had three sets of McGard lug nuts on three different vehicles going back more than 10 years now, and they've never rusted....

Anti-seize or not, even using only hand tools to remove and tighten as I (and probably you) do, keep those two-piece lug nuts long enough and they will eventually get loose on you....

 

I have had problems with these on all three of my Jaguars. They are a pretty crappy design for such a car. Even my local dealer agrees and gives me free replacements whenever I have one start spinning or come apart.

If you must have a whole new set, then these are the correct style:
http://cgi.ebay.com/ebaymotors/Jagua...spagenameZWDVW

These are not the correct style and are not safe for use with factory alloy wheels:
http://cgi.ebay.com/ebaymotors/20-JA...spagenameZWDVW