Tires with an outside diameter of 677mm (26.7") do give an almost perfect speedo indication (speedo against GPS speed).

This diameter is for the OEM 16" (225/60) and the 18" (245/45 and 275/40).

The often used 255/40R18 is slightly smaller in diameter.

 

I guess as long as the speedo is correct that's more important.

The tire table inside the armrest on my XJR lists 255/40r18 as the size to use on the Pentas. I hadn't thought to check the speedo against gps yet.

 

Yes, that is an OEM size for the Jaguar 8J and 8.5J rims, but slightly smaller in diameter.

 

Hi Ericjanse, I was wondering regarding your wheels anf Grever's Wheels, what was the pcd and the center bore diameter ? Did you guys have to use adapters ?
Cheers

 

I can't answer for Grever's, but my wheels are Jaguar OEM, with the Jaguar standard dimensions, no needed to wiggle, even the center caps click in .

 

Not sure where you're located, or what your budget is, but have you considered these?
https://www.jaguarforums.com/forum/p...-extra-176241/

 

Hello, thanxs for the link and the tip :-)
based on the specs, there would be less Inner Clearance by14.7mm less. Is this safe, do I need to modify anything ? What is the maximum I can reduce the inner clearance without altering the inside...I would rather roll the fender lips
Cheers

 

Hello, thanxs for the info. Regarding your info, How did you handle the Inner Clearance (14.7mm less) ? Did you have to make any modifications ? what is the max safe inner clearance you can reduce rear and front ?
Cheers

 

thanxs for that info, based on your set up am i right that you reduced your inner clearance by about 15mm on the rear ? did you have any issues / modifications to do ?
Do you happen to know that is the may inner clearance reduction you can go for rear and front wheels ?
Cheers

 

9J with an ET35 will fit at all 4 corners.
Forum member Stu got 9J all around.

But I don't think you can go any wider than 245/45 or 255/40 in the front due to scraping (as specified earlier), and my own personal opinion is that 9J is too wide for 255 tires, they will protrude inwards.

 

Ok thanxs for that, I kind of figured that 8.5 in the front would be good although you can go to 9. However, I am looking at fitting 9.5 at the rear...and as you explained before this has been done. But I am worried about inner clearance rather than lip rubbing (because I can roll them lips up ;-). So do you know what is the max inner clearance reduction you can go ?
thanxs for your help

 

I have personally run 15mm less inner clearance and 28mm less outer clearance (front) with no problems.
One the rear I run 17mm less inner clearance without issue. My rear wheels extend 33mm more outwards but you need fender lip trimming/rolling.

Previous setup: OEM Milan wheels (which I am selling)
18x9 et35 255/40/18 front
18x9 et35 264/40/18 rear.
No rubbing. I even temporarily had to run the 265/40 rears on the front and there were no issues.

Current setup:
18x9 et18 255/40/18 front
18x10 et25 295/35/18 rear
No issues on the front. Need fender trimming/rolling on rears.

I don't agree with ericjansen regarding 255 on 9" wheel. 255 is the perfect width for a 9" wide wheel. There is no bulge or stretch. In fact that is the recommended width by the manufacturers. Even 10" is ok. An 8'' wheel is too narrow for a 255 tire.

 

Jesus Christ...This is the information I have been looking for ages...Fantastic !!!! You made my day

 

Hello friends:
Just want to check something with the experts.
2002 xj8

Will this wheel fit on the car?
18 x 8.5
+20 offset
5x120.65
83mm hub

 

You will need a hubcentric spacer from 74.1mm to 83mm, I couldn't find any online when I looked for that size a while back so you would probably need to take the ones that were 71mm ish ID 83 OD and machine the middle out to the right size. Other than that it should fit, but 18.5 might be a hard dia to find tires for...

 

Although there are others who say that everything will fit , I dare to say that a 255/40 on a 18x8.5J will rub on the rear fender lip while compressed.

For the rest what Nilanium stated, I guess you have a typo in your sizing.

 

Yes, typo.

The tires im putting on are 255/40/18
The tires on there now are 225/60/16.

By my math, when installed, there should only be a wheel height difference of approx 18mm.
Since the wheel will be taller, but the sidewall is shorter.
Right now I have a lot of clearance in the tubs. They should fit, but if not, then a spacer will do.

Thanks for the replys

 

You mentioned a +20 offset, plus a wider tire and rim. I dont see how a spacer is going to solve things IF they should contact the lips.

 

Awesome web site for figuring out wheels and tires
This is great
Just checked mine.
it seems that going from a 225/60/R16 to a 255/40R18, the circumference is actually slightly smaller that stock.
It's @ 2.25% of stock.
Within the 3% tolerance.

Try this:

Tire Size Calculator - Tire & Wheel Plus Sizing

 

I am not talking about your outside tire diameter (which indeed might help you a bit), I am talking about the outer point of the tire.

You will use wider tires and wider trims, AND you will use a smaller ET (from 33 to 20), which will push the tire even further out.

Your tire will normally retract into the wheel well if ~3/4 or more suspended, and a wider tire WILL at some point hit the fender if you go too wide.
In your case the tire will be almost 3cm wider.
You will be on the very limit if you will clear the lip, probably JUST, with the thickness of credit card between the tire and lip.

And use this calculator, much more complete, not only giving you the changes in tire and rim, but also the surroundings:
https://www.wheel-size.com/calc/?whe...=30mm&scl=50mm