The biggest I have seen on an X308 are the 20" Detroit XKR wheels. But the ones I think might be a bit better are the 19" Apollo wheels from the later mk1 XK8.

 

I would agree that 20" would be the biggest wheel that would fit, I too would probably opt for something like a 19" as I think the 20" just looks too big under the arches of a X308/X300

 

Have seen one with 22" but it does look silly 20" is the largest from the Jaguar range of standard fit wheels.

 

These are the wheels I am on about, I think they are a nice design as well.

 

They look superb 8)

 

20 inch fit the X300/308 no problems (depending on width and offset). I have been running aftermarket 20s on mine for over 2 years now

There is very few around the world with 22 but IMO they look stupid, plus speedo would need recalibration, guards rolled, etc


Just note the XK8 might use staggered wheels I seem to think? Wider on the rear than on the front?

Widest rims I have seen on the X308 is some of the Jag BBS style 20" that were running 265 tyres, and it looked a bit mis-matched really, just a tad too wide for my liking

According to a site I usually go by, the X308 can handle largest as 20x9 inch, however I dare to say 9" is too wide for my liking

 

You are dead right with the XK8 having larger wheels at the rear to the front

The wheels on my XJ taken from an XK8 are 8x18" front and 9x18" at the rear

 

Ah so the XJ can handle staggered from the XK then? Good to know

What width tyres are you running on the rears on your XJ?

 

Well, when I bought the wheels I assumed they were 18x8 front and rear so ordered tyres in advance of 245/40, however, when I collected the wheels I then realised rears were bigger, so I could have gone for 255/40 on the rears and 245/40 on the fronts

When they have worn out Ill switch to that setup, which probably wont be that long

 

I have the 18 inch penta alloys on mine with 255/40/18 on all four wheels, whats the width on these alloys, and anychance of some pics of your car with the 20 inchers

 

Penta are 8J wheels. If you want to put 20 inch on a X308 you need to fit XK fronts all round ie 20 x 9J.....and use 255/35 20 tyres. PM me if you want to buy some wheels!