Hello!

I figured it would likely be best to ask this question here as the X305 forums is usually a little sleepy/more focused on documenting/addressing V12-specific issues.

This weekend I scored BIG TIME on Facebook Marketplace with an incredibly nice set of 18in BBS Milans in Oyster! They appear to be nearly new take-offs with a set of 2004 date-coded, but clearly brand-new Michelin PS1s!!!. Since the price was basically like committing highway robbery, I didn't inspect them too closely based on my (incorrect) assumption that Milans were only available on R1 package X308 XJRs.

Once I got them home, however, I discovered mine are actually a staggered set and after some more digging, I found an old R Performance brochure detailing that, in-period, Staggered Milans were available for X100 XKs. With that in mind, I'm now trying to figure out what tire sizes I need to run these on my 1995 XJ12. Here are the sizing specs of the XK Milans I have:

• Front: 18x8.5 +33 (Identical to XJR Milans)
• Rear: 18x9 +35

Currently, they are sporting 245/45s on the front pair and 255/40s on the rear, but I think I have some room to play with when choosing new tires. That being said, I have a few requirements:

1. I'd like as much sidewall as possible. The XJ12 is supremely comfortable and I don't want to detract from that amazing comfort too much
2. I will not roll the rear fenders.
3. I'm willing to make modifications to the bump stops if necessary

For context, my XJ12 is an incredibly well-preserved 41,000-mile creampuff, and any modification I make to it, I'd like to be completely reversible. Unfortunately, the selection of tires in the size, weight, and speed rating for XJ12s is pretty dismal and I am a snob for running Michelins on anything I can. Additionally, my stock 20 spokes were chromed by the dealer when it was new and they're beginning to pit/leak...

Taking all of that into consideration, XJRs usually run 255/40s all around, so I was hypothesizing of using that size on the fronts, but there's very little information out there on rear wheel/tire fitment on these cars. I was originally thinking of 256/40s or 275/40s, but have no idea if they'd fit without modifications. Additionally, I've read that X300s are a little more sensitive to tram lining than X308s when fitted with wider tires so I'm not sure 255/40s would even be appropriate for the fronts. Has anyone on here used XKR wheels or any other wheel with similar offset/width in the rear, and if so, what tire sizes did you use? If not, does anyone have any suggestions or advice for tire sizes that would work well with these wheels?

TLDR: OP Bought XKR staggered wheels, and would like to know the best tire size to fit in the rear without rolling fenders.

 

225s are the recommended.from reading others as this has to do with front tramlining

Your V -12 being heavier than the inline 6 may come into play

 

If you look from the top down with a light from below you might see a common gap in the steering rack and the mounting block on the car chassis

There is a aftermarket shim you can install at the tip of a pry bar in the pic without removing the rack or rods as the shim has a split in it

Jaguar part SPC1059

I just ordered mine from a E - bay vendor in France , M' Lady Penelope is going to like them as I didn't get anything for her this valentine day . you know she is the prettiest Jaguar on the whole block . just ask her

See this link from moderator Don

Steering Rack Stiffening Bushes DIY - Jaguar Forums - Jaguar Enthusiasts Forum






This is a pic of one side installed with the retaining wire loose . in this pic the shim is gray

 

Sounds like a great score! Those are nice wheels. They can be pricey, especially a staggered set.

Try them on for size as they are now. I think the fronts will be ok with that tire size. The rears... I'm not so sure a 9" rim and correspondingly wider tire would clear the fender and exhaust pipes on the XJ12 without some mods.

Do the current tires look like the right width for the wheels? You don't want to scuff them up. Also, your rear diameter/sidewalls might be visibly shorter given the sizes as they are now. The rears would have to be even wider to give more sidewall height, given the ratio of 45 front to 40 rear.

The rear wheel openings on the X100, the XKR being the origin of your score, look huge. I find that a real distraction from an otherwise beautiful Jag. Apparently they can accommodate up to 20x10 wheels! Although the X308 XJR could be fitted with the 8.5" Milans all around, I don't know if it's exhaust pipes are repositioned compared to the X300.

I haven't noticed much tramlining with my new 245 tires, and I haven't shimmed the rack. The shim kit is a good idea with wider tires.

JF Tire/Wheel Size Calculator

 

i can't tell you off the top of my head for 18's what you need but there is tyre size calculators on the web.
https://tiresize.com/tyre-size-calculator/

put in the factory size. and then you can see what sizes match the outer rolling diameter, width

it won't help you work out what the biggest you can fit without scraping is, but it will help you see what matches OEM spec.
i am running 20's on my car atm with 245/35/R20 and that is as close to the factory 225/60/R16 that can get. they drive nice. i do feel the road more than i should due to the tyres being akin to rubber bands. but it drives nice. i can not compare to stock tho as they were on it when i got the car. i get no scrubbing.
as parker says the car can fit 20x10 and i am almost there.

the XJR came with 255/45/R17 so i would suspect aslong as you don't go taller/wider than that you should be good.
so that would make it 255/40/R18

**edit** although some doo seem to say tramlining happens on the stock 255 and going narrower helps.

 

maybe i should look at the shim kit.
@Parker 7 let me know how it goes for you.
also share me the link and an idea of how it is to install.
as with the big fat *** sexy 20's it may be worth an idea.

And your Penelope likely would be the prettiest on your Block.
I know my Kitty is the Sexiest over my way.

 

There were only 9 sets left from the vendor at the time i odered mine

 

Thank you for all the feedback! I had no idea that the steering rack bush was available so I'll definitely be purchasing that before dropping my subframe.

As far as the tires on the wheels already, I wish I could test fit them, but the wheels/tires are with me in Texas at the moment and the car is at my parent's house in California... As far as the tires on there at the moment, the fronts are 245/45R18 and the rears are 255/40R18. After playing around with the tire calculator a bit, it appears 255/45/18 would actually be the closest to the stock 225/60/R16 size and only be .4in closer to the inner frame than your Laminas @SleekJag12 . That being said, I found an X308 owner last night who claims to run 275/40R18 on the rear of his VDP on identical spec XKR wheels. so I'm interested to see what he had to do to make those fit!

 

the steering rack shims are a must for any x300 owner - the amount of movement in the rack without them is pretty excessive.
They are a real pain to fit though - especially on the side with the input shaft.
I see most people fit them with the rack removed from the car to make prying the gap up a bit easier.

 

After much deliberation and measuring, I decided to go a size narrower than originally recommended to me by an X308 owner. I settled on 265/40 in the rear and 235/45 in the front. This gives a rolling diameter of 26.3in which is identical to the stock size on the X308 VDP Supercharged. After "halving" the stock bump stops theres plenty of clearance both with the inner fender and the fender lip at full compression. No fender rolling was required. Overall, this combo almost looks like it could've been offered from the factory which is exactly what I was looking for.

Additionally, I have not installed my steering rack spacers, but on my initial drive across multiple different pavement types I experienced no discernable tram-lining

 

Those tires are beastly!! The wheels transform the look. They will bring out the sporting nature of the V12's power! Well done.

No trouble with the exhaust pipe clearance? My car was a very close fit but only on the right side. That pipe must be slightly out of place.

An airplane hangar for a garage? Well that could work I suppose..........

 

No interference with the exhaust at all! Only modification were those bum stops. If you wanted to look more correct under there, you could technically buy XJR-R1 bump stops, but cutting my old ones in half was free so I opted for that.

Not quite an airplane hangar, but I can see that it looks close! Its actually 4 40' shipping containers shaped in a U with a half-height barn kit for the roof portion. Super cost effective solution for a lot of space!