Toyota oem nuts are also wrapped in SS, they also fail and the reason for the availabe aftermarket solid steel plated nuts as there are SO many more of them out there than Jaguars.
Not a problem for many of us, but the plating quality on the cheap nuts is poor, seen cracking and rust stains on our Toyota's, have a set ready for the XK "when" the wheels come off one day.
By the way, 19mm is .748ins and a 3/4in 6pt socket will be just fine...
Regards

 

 

I, too, have a full set of metric sockets that I keep in my garage.

Just make sure that you have a breaker bar that fits those lug nuts in your trunk. Otherwise, you'll be unable to put the spare tire on when you get a flat.

If you don't already have a rubber-coated deep socket that fits your lug nuts, I recommend buying one and keeping it in your trunk together with a ratchet handle and extension. I also keep a torque wrench in the trunk. I bought the socket and torque wrench at Harbor Freight and recommend them. Once loosened with the breaker bar, the rubber coated socket protects the rim from damage and the ratchet handle makes quick work of removal and reinstallation. I also recommend keeping a 12 volt tire inflator in the trunk, in case you have a slow leak and don't want to put on the spare.

Be prepared!

 

 

I feel your pain! I, too, had no spare tire because my XKR has Alcon brakes. But I wasn't comfortable driving around for 2 years with the 12 volt inflator kit and no jack or spare tire. Here's how I was able to put a spare in my trunk with all the factory tools:
https://www.jaguarforums.com/forum/x...-brakes-67260/

You can do it, too. Because you have a 5.0L, you might not need the custom spacer that I needed to clear my rear Alcon rotors.