Had to change a front tire on Superblue yesterday and discovered that one of the 5 lug nuts was larger in diameter than the rest. In fact, it was too large for the factory tool to remove and was even slightly bigger than the biggest socket on my standard 4-way wrench. I was only able to loosen it by putting the biggest socket on it and whacking it a little with a hammer. IIRC, it was also this way on one of the rear wheels of Supercat, my ';95 coupe. What gives? 
Hi. Is it a wheel lug nut or has someone jammed the locking wheel nut key on two of your wheels and just left them there. My 95 should have the same lugs as yours but the nuts are 22mm and the key is nearly a mm bigger. Another possibility is that originally all the nuts had chrome caps on to make them look better. This did make the original wheel brace a little tight in the case of my car. Has your car still got those or have the majority of them either lost their caps or been changed for ones without? Hope this helps. Cheers. Richard.
Paul,
Had exactly that problem on a newish Range Rover. Just two of the lug nuts were oversize of the 16 fitted (the other 4 being locking nuts) and the 22 mm factory wrench would not fit. To undo them I had to use an old worn 22 mm socket and hammer it over the two oversize nuts. On the Rangie, the flanged lug nuts have a thin chromed decorative ātop hatā pressed over the hexagon. Are the ones on your Jag a similar design? I can only conclude that a batch of lug nut ātop hatsā were stamped from minutely thicker metal thus increasing the āacross flatsā dimension so that the standard 22 mm wrench wouldnāt fit.
When I complained to my friendly LR dealer they immediately supplied two replacement nuts of the correct size without question - so I presume they knew all about the problem!
Moisture can get between the ātop hatā and the nut. When it freezes, the water expands and makes the overall diameter larger.
Well Paul what was said before is correct but I opened this thread expecting some personal observation or problem!
LOL - I guess Mr. Limey had similar thoughts ā¦ 
I saw the title and immediately wondered if the new forumās picture upload facility is a good thing or not.
After reading Paulās title I felt compelled to send him a PM suggesting surgery. Itās happened to me too. (On an old Buick)
Moisture can get between the ātop hatā and the nut. When it freezes,
the water expands and makes the overall diameter larger.
I didnāt know any Jaguars came fitted with those cheap-@$$ capped nuts.
My foster fatherās 1960ās AMX came with them. He took it to a tire store for
new shoes, and the next day we noticed that a couple of the lugs had plain
iron nuts in place of the original chrome acorns. Went back to the tire store
and raised ^&*(^ about somebody stealing his fancy chrome nuts. Then they
showed us that the chrome was just a stamped wrapping around plain nuts
and that using an impact wrench must have caused a couple of the caps to
fall off. Sure enough, a couple of the others had cracked along the corners
of the hexes and were ready to fall off soon.
I personally wouldnāt own such garbage, Iām sorry. If I had a car that came
with that junk, Iād roll right down to AutoZone and buy a whole set of
aftermarket chrome-plated lug nuts. IMHO, that level of shoddy
manufacturing is unacceptable, pure and simple. Even my Japanese
appliances are made better than that. I was miffed I had to replace the very
nice chrome-plated nuts on my 2004 Honda Civic because they were
incompatible with my aftermarket alloy wheels; I had to buy a set of ātunerā
nuts to work with the wheels.
ā Kirbert
have those cheap nuts on my Durango, they are garbage. when in new condition, they are fine but the chrome part swells and requires beating the socket on with a hammer. this loosens the caps and they eventually fall off leaving yet another size nut that is neither standard nor metric. this ALWAYS happens when it is the only vehicle at my shop so I go to my coffee cans of old lug nuts and find one with the right diam. and pitch but no concern of socket size. I have different size nuts that all fit properly. it is likely the p.o. or shop he took it to stripped a nut and threw on what he had. my concern would be that it is correct pitch and diameter.
my concern
would be that it is correct pitch and diameter.
Fortunately, most everything seems to be either 1/2" or 12mm these days,
and all of some standard pitch for each size as well. I presume big
pickup trucks might use larger lugs, but I donāt buy such vehicles. There
are a few other things to be concerned with, though. If itās a steel
wheel, the lug nuts will typically have a conical seat ā unless itās a
Honda. Honda steel wheels use a unique spherical seat on their lug nuts.
If the wheels are alloy, they can use lug nuts with deep shoulders, lug
nuts with shallow shoulders, or the same conical seats the steel wheels
use. I was really surprised the first time I found a set that used conical
seats. Then, of course, thereās my aftermarket wheels which require
ātunerā lug nuts. Iād love them if only I could find a set with a decent
chrome plating job; the ones I have keep getting rusty even though they
look nicely chrome plated when new.
My 1973 Triumph GT6 used some sorry little lugs, 3/8" I think. Bought a
set of tires and the tire shop snapped all the lugs off with an air
wrench. I bitched and talked them into paying for new lugs and nuts, and
I would install them myself. That worked GREAT, because I found a set of
1/2" studs that would fit right into the same holes the 3/8" studs were
in. So I just knocked out the 3/8" studs and threw them over the hedge,
pulled in the new 1/2" studs, and reinstalled my alloy wheels.
My 1963 Oldsmobile had left-hand thread lug nuts on the left side of the
car. I think lots of cars did in those days. Whassup wit dat?
Eventually that idea went away.
ā Kirbert
I had a set of used momo rims I purchased for my xjs. came with lugnuts. the lugs went on a little loose but threaded on fine, even took āsomeā tightening but stripped out as I torqued them. after stripping several, I took the 2 seconds required to read the size stamped on them only to find they were metrics and needed standards. the left hand thread idea was in belief that it would spin in the direction that would tighten it. like a screwgun in reverse loosens the bit?
Iām thinking thatās a good idea for my situation, Kirby, so I donāt get stuck out somewhere with a flat and canāt get one or more of the nuts off ā¦ So, what size would I need?
I went ahead and looked at AZās Ebay listings for nuts, but they warn in fine print that the one recommended for our XJSes ādoes not fit OEM wrenchā. So, I checked around and found these, will they work?
So, what size would I need?
I wouldnāt trust anyoneās opinion. The lugs on my '83 were 1/2", but Jaguar
was switching lots of things over to metric in ā84 so thereās no tellinā. Take
either the car or one lug nut with you when shopping.
And remember: Itās not just the thread size thatās important. If you have
alloy wheels, each nut will probably come with a flat washer, and itāll have a
shank that slides down into the hole in the wheel. Those shanks come in
two depths, a short one thatās only perhaps 1/4" long and a long one thatās
nearly an inch IIRC. What you get doesnāt need to be exactly the same
length as what you have, but it needs to be close enough that the flat washer
tightens up on the wheel before the shank hits the bottom of the hole. And
using a short shank when the wheel calls for a deep shank simply reduces
the thread engagement when the lug nuts are tightened.
Also note that the hex size on your replacement lug nuts is likely to be
different than the Jaguar nuts. On my '83, the hex size was huge for some
reason; aftermarket lug nuts used a much smaller socket. This is important
because the tire changing tools need to work for you or you wonāt be able to
change a flat. On my '83, the lug wrench was also used to operate the
scissors jack via a hex on the jack, so either I had to carry a wrench to fit that
as well or change the hex on the jack!
I actually went through this debacle twice. When I bought my '83 it came
with Dayton wire wheels fitted with stainless steel deep-shank lug nuts.
Stainless steel sounds like a great idea for lug nuts, but these were awful.
They galled something terrible and stripped the threads off several of my
lugs, and the lugs arenāt easily replaced on the XJ-S. After repairing all the
damaged lugs, I replaced those SS lug nuts with an aftermarket
chrome-plated set from AutoZone. They looked far better, because the
chrome nuts looked correct within the chromed wire wheels. But I had to
carry two wrenches to operate the scissors jack and change a flat. I
eventually swapped a different hex on the jack to go back to a single wrench.
But I soon figured out that the Dayton 60-spoke wheels were garbage, and
they were overweight as well. I found a business in Sarasota that gave me
an acceptable deal, trading my Daytons for a set of stunning wheels from a
Vanden Plas. The lug nuts swapped with them, and the Vanden Plas wheels
have covers that hide the lug nuts, so they came with a set of plain black
(Cadmium plated?) nuts with a great big hex. The hex was evidently the size
my XJ-S originally had because it was the same as the jack, so I promptly
swapped the original hex back on the jack and put the original lug wrench
back in the trunk.
But no, nothingās ever that easy. Somehow I got two of the wrong nut. They
had the correct thread but were a smaller hex, so I had to carry a second lug
wrench once again. Aaaargh! A couple of brand new Jaguar lug nuts would
fix that, but I had sticker shock at the price. I dropped by a local junkyard
and talked to an old geezer there about it, and he pointed to a barrelful of old
lug nuts and invited me to have at it. After a LOT of digging, I came up with
a couple of rusty old lug nuts that were the correct thread, correct depth of
shank, and correct hex, but they were perhaps twice as tall as the Jaguar
nuts. Bought them, took them home, chucked them up in the vice, and
sawed the upper half of each nut clean off. Ended up with a couple of ugly
nuts that were exactly the same configuration (and weight!) as the other 18
genuine Jaguar nuts, they just had flaking chrome and rough-sawed
surfaces instead of Cadmium plating. Since they were hidden by the covers,
who cares?
ā Kirbert
So, I checked around and found these, will they work?
Do your lug nuts show? If yes, most people insist upon āacornā style nuts
meaning they have a closed end, you canāt see the stud or the threads when
installed. Meanwhile, on wheels with covers so the nuts are hidden, quite
often regular nuts are used so the threads are plainly visible. I kinda prefer
the acorn type even if hidden because thereās less opportunity for moisture
to get in there and rust the threads, but if hidden sometimes thereās not
enough clearance for the height of an acorn nut.
You also might want to think about whether you really want to stick with the
original lug wrench. That hex was HUGE on my '83, far larger than
reasonable. That means they weigh more than they should, and itās rotating
and unsprung weight. That and the fact that lug nuts with regular size hexes
are far easier to find and cheaper to buy are good reasons to ditch the
Jaguar size and go with more conventional size lug nuts. You just have to
make sure your tire change tools are compatible. A new lug wrench is
cheap, but you might have to revise or replace your scissors jack.
You might want to anyway. IMHO, that OEM scissors jack isnāt exactly a
paragon of safety. A nice hydraulic jack might make a nice upgrade.
No matter what route you go, be very sure to apply anti-seize compound to
the threads on those lugs before installing the wheels.
ā Kirbert
I do recall left threaded lug nuts on one side and right handed on the other. Several makers did that. RR included at one time. One of the lessons Iearned
at my college job ion the late forties. Chrysler marked theirs with L and R.
The idea was that centrifugal force would unwind them. Since debunked. Why Ok on one side, but not the other? Got me?
Carl
[quote=āKirbert1, post:16, topic:350643ā]
Do your lug nuts show? If yes, most people insist upon āacornā style nuts meaning they have a closed end, you canāt see the stud or the threads when installed.
[/quote]Yes, Iād like to stick with the āacornā style, if possible, and still use my OEM wrench. I noticed though that many of the acorn style being sold on Ebay, they mention they do not have the ābuilt-inā washer that is on the bottom of the OEM nuts. Is this important, even if I use anti-seize under the nuts? If so, then I guess I could put manual washers on each of them when mounting. 
that was cuteā¦the syndrome was named for the oriental philosopher wun hung tu lo
I noticed
though that many of the acorn style being sold on Ebay, they mention
they do not have the ābuilt-inā washer that is on the bottom of the
OEM nuts. Is this important, even if I use anti-seize under the nuts?
Yeah, gotta have those. I donāt think Iāve ever seen anyone sell lug nuts
without them, though.
ā Kirbert