Hello I was wondering how big of a wheel I can put onto a 1998 jaguar xj8? I'm not going to put any ridiculous 28's on it or anything like that I was thinking that 20 or 22's would complement the car without making it look ugly and ridiculous. would I have to upgrade the suspension to put 22's on it? obviously upgraded brake calipers is a given in any wheel expansion.


I want to put 22 inch Milanni Stalker (Chrome with black inserts) rims on a black jaguar.

 

You're in the X350 section.

 

Above 20 starts to look silly, the wheel arches just aren't designed for it - not even getting into comfort and ride.

18" will show little to no change in how the cat feels and acts, 19 I think is the best compromise between size, style and comfort and I really think that 20 is the extreme end.

These are just my opinions however, feel free to put 34"s and donk that thing out if it makes you smile - its your car.

 

Keep in mind that the X308 is at its heart based on the XJ40 platform that debuted in 1986, and therefore the wheel openings were designed for the wheel sizes of the time, which were usually 16" at largest. With that in mind I agree with the others that 20s are about the limit that look good, or that really even fit without a lot of effort. I agree with Probesport that 19's are a good compromise on the car, but I have seen 20's look very good on the X308's, like the several I've seen on 20" Detroits or Sentas. But even they look a bit too big IMO, I can't imagine going any bigger. And it's very hard to get a total tire diameter of more than about 27" into the front wheel wells without rubbing during turns, which on a 22" wheel means you'd have to run a VERY short sidewall on the tire, meaning your ride quality would be rubbish and you'd be very likely to damage your wheels and/or tires on the road. I'd stay to 20" or below, but that's me.

And you wouldn't have to do much to your suspension, but obviously larger wheels are heavier and put a lot more strain on the suspension components. The X308 is hard on wheel bearings already, and large diameter wheels will just make that worse. And like you said, a brake upgrade wouldn't be a bad idea at all to handle the extra rotational mass. You could just upgrade to the XJR components which is an easy and affordable swap and should be plenty big enough to handle the extra stress.

 

I have 20" Senta Chrome staggered on my X308 XJR . that is the max size I could put on X308 to remain proportional and functional.

I have very little clearance with wheel adapters on becuase of bolt patten conversion

they actually weight much heavier than my stock asteroid

 

I put 18 inch Asteriods on my xj8. 255/40/zr18 looks and feels great. Just me though.

 

@Cabezagrande- Thanks, your the only one that actually answered my questions instead of stating there opinions. how much would the JXR components cost me?

 

22s only fit with a lot of modification and in all honesty look far too big/ridiculous even on a LWB XJ, but you get away with 20s easy and look good

 

I apolgize for not addressing your statements directly. You are wrong on both counts, you do not need to upgrade calipers or suspension just because you go up in wheel size.

Pay attention to rolling diameter. As long as your new combo does not exceed your factory not a single change is required.

 

You'd need the XJR calipers, rotors, and some pads for the new calipers. The calipers look to be around $90 a piece from RockAuto for reman'd calipers with new hardware, so about $360 there. The front rotors (325mm) are about $65 a piece, and the rears (305mm) are about $50 a piece. I'd go with Akebono Euro Ceramic pads, and they're $65 for the fronts and $60 for the back.

To clarify, upgraded brakes aren't strictly necessary. Your stock brakes will do OK. But, larger diameter wheels are MUCH heavier and due to rotational inertia, the bigger your wheel the harder it is to stop, even if they were the same weight. So larger wheels are significantly harder to stop, and it'd be nice to counteract that with some bigger brakes that are more capable of handling the added stress. XJR brakes are just the easiest and cheapest meaningful upgrade.

But, 22's will be VERY hard to fit in the wheel wells without modification. I'm currently running an 18x9.5 wheel in the front with a 265/40/18 tire, so an overall diameter of about 26.35 inches. I am VERY close to rubbing on the inner fender well under full lock, and am as far inboard as I can get with the wheel. I don't think you'll be able to get more than about a 27" tire in there without modification to the wheel well. On a 20" wheel, this still leaves enough room to get a 255/35/20 tire in there, which has a decent amount of sidewall. With a 22, you'd have to go down to a 255/25/22, which is basically painting a little rubber around the wheel, with a VERY high likelihood that it'll be damaged on the first big pothole you hit. The X308 was just never designed with super large wheels in mind, so the wheel wells just aren't that big. If you're willing to take it to a body shop and have them start pulling the fender lips and doing some cutting and fabricating of new inner fender wells, the sky's the limit. But I really think 20s are about the functional limit under the stock wells.

 

There is some good information there ^^ however the fact that the wheels will be heavier is a blanket statement.

If you buy heavier wheels they will be heavier, if you buy lighter wheels they will be lighter - regardless of rim size.

All things being equal, the change is negligible below are some maths for the scenario I was looking at for my own changes of 16 vs 19.

Factory (225/60/16)

Rolling radius .33820m

Tire sidewall inertia .11455 kg-m2
Tire equivalent mass 8.6018kg
Tire equivalent mass ratio 1.90

Wheel inertia .12174 kg-m2
Wheel equivalent mass 5.7833kg
Wheel equivalent mass ratio 1.27

Aftermarket (245/40/19)

Rolling radius .33930m

Tire sidewall inertia .10024 kg-m2
Tire equivalent mass 8.7862kg
Tire equivalent mass ratio 1.94

Wheel inertia .17167 kg-m2
Wheel equivalent mass 6.2948kg
Wheel equivalent mass ratio 1.39

So combined mass of each scenario (A= 14.38, B=15.01) is nearly non existent. This becomes a concern for professional drivers where perfection is demanded and milliseconds count - but not so much for your avg XJ driver.

 

I'm running 22's with 285's all round...... It definitely takes a lot of modification

 

what did you have to modify? I'm probably going to get some tires a little smaller than that in height. it looks hard to take a turn in that.

 

He's removed the arches and is building new, custom ones

As said above, you can fit any size you want as long as it fits into the original envelope of the factory tyres. But the general consensus is that 20" is as big as you would want to go without it looking silly.
Also you run the risk of it looking like a rollerskate if you don't lower it slightly. Perhaps consider upgrading to XJR suspension.


Oh, and if you're going to be pedantic about people not being specific about answering your question, perhaps you should make your question a bit less ambiguous.
What are you actually trying to do with your car? Also, a quick search on google will find all sorts of wheels fitted to X300's and X308's, but this is the only place I've found where people will actually offer advice and experience with different sizes and offsets. There are plenty of other threads on here, try looking back at the last couple of pages of threads, there's A LOT of great info

 

What grandell says is right, I have had to remove the arches, cut the chassis back, lose about 3 inches of the sill ends back and front, with these particular wheels they require the rear doors welding up which I was going to do anyway......

Don't go 22s if you want an everyday car, I am doing it for giggles it will probably tramline and handle like a pig but that does not matter to me

 

I prefer to stay OEM and avoid the pitfalls of fit and improper spacing and risking stress on suspension components and body. I do not need bigger wheels to compensate the OEM 18"
are adequate.