I apppears that from the number of posts about tyres (tires , yankie), there remains considerable anguish about sizes and brand that are suitable for the XJ40. My Sov is a 1990/91 -build date July 1990 by Ford. Only 146,000 kiloms.

The correct size is clearly listed in your owners Manual & to that end, I have included the page from the "Specification " section. (see attached).

Of course, many members will screem that the 225/65.15s are not available so the suggested alternative is a Kendra either at 225/70 R15 or 235/70 R15. Do not have a narrower put on you by some ignorant tyre dealer as that will produce considerable oversteer. From a practicable point, I like a bit of understeer. Finally, there are some sites on the web that have very helpful tables as to the overall tyre sizes. This enables you to see if the tyre has only modest changes or they are dangerously oversize or undersize.

Hope this is of some help.

Regards,
Michael Prichard
Melbourne Aus

 

Its been a long while.

The daughters '40, was once Metric, and has 15" ROH mags on it. She runs 235/60 X 15 and has done so for, as I said, a god long while.

I also run those same spec on the V12's where 215/70 X 15 were the standard spec. Again, with no issues. 80K kms out of the last set of GoodYear on the Red Terror.

 

I believe ford rims will fit it - right? Same stud pattern? I could be getting my years wrong however...

 

Grant in Adelaide.
I am not sure that your contribution is all that helpful when the tyre size you have on your Daughter XJ40 are undersize by
Rolling Radius-5.25mmCircumference-32.98mmDiameter-10.5mmWhen your speedo reads 100km/hr you're actually at 98.42 km/hr.


Perhaps a more considered approach to safety is in the best interests of all members.


Regards,Michael Prichard,
Melbourne. Aus

 

Dont follow??????????

At least the car is slower than the speedo, and Jag speedo are SOOOOOOOO accurate HAHA.

Safety is in the hands of the operator much more than the equipment being used, unless you are a Pollie, then its everyone elses fault no matter what.

As for tyres, if what came with Dinosaur car is NO longer available, you have to compromise, or junk the car, same goes for Cross Ply tyres back when I started driving, that are replaced with radial tyres.

My BlackS Type has the CORRECT tyres on it (Pirelli), at the CORRECT pressures, and the speedo reads 100, and the radar gun says 97, I am NOT worried one bit.

 

I don't follow, either.

The slight dimensional differences mentioned are not very significant and I can't see them as being a safety factor at all, and Jaguar used several different sizes over the course of XJ40 production anyway.

If there's a safety issue with tires it's most likely from choosing the wrong *type* of tire....wrong tread design for driving conditions, incorrect load rating, or improper mixing types/designs.

Actually, the *biggest* safety issue with tires is underinflation/neglect! Too few people regularly check pressures or inspect for damage.

FWIW, here in the USA only .5% (one half of one percent) of accidents are tire related. As you say Grant, the biggest safety factor is always the driver.

Cheers
DD

 

Not Ford.

GM.

At least thru the X308 series Jaguar used a 5-on-4.75" bolt circle....same as used on many millions of GM cars. The difference, though, is that the Jaguar hubs are larger than most, requiring a larger center hole in the wheel.....that's where it gets tricky.

Cheers
DD

 

I might add that, when considering physical measurements of tires, we should also remember that manufacturing standards are very loose.

For example.....

Using manufacturer supplied information I compared about a dozen 225/60x16 tires. Tread width varied from 6.9 inches to 8.0 inches and diameter varied (get this!) from 25.6 inches to 26.8 inches!

Even if we throw out the 25.6 as a typographical error, there is still a range of 26.3 to 26.8 inches in diameter...about 12.5mm

So, obviously, tire size *designation* alone does not guarantee anything. If a few millimeters difference in dimension is the difference between 'safe' and 'unsafe' (a notion I disagree with) then we can't rely on recommendations based only *designated* tire size.

Cheers
DD

 

To our friends in the USA.


It is not unexpected that you do not follow the importance of the correct tyre sizes (you should check your car insurance). You do have an unenviable reputation for being a bit "gung ho". Perhaps advising members to exercise caution when putting non-standard equipment on Jaguars is a more considered and well educated approach.


As for Grant in Adelaide, I do hope is is not an ex-employee of Sovereign Motors.


Regards,
Michael Prichard
Melboune Australia

 

Oh, but we do. It's just that many don't believe that only ONE tire size can be safe when we know darn well that any numbers of sizes can be safe....if you do a bit of research and thinking.

For that matter, you can select the correct *size* and still end up with an unsafe tire if you don't take other things into consideration.

Now, I'll grant you that there are some morons out there who don't give tires any thought at all. They're at the mercy of their own stupidity.



We do. They don't care. In fact, besides asking my insurance company I've asked several claims adjusters about tire spec versus insurance converage and they've all looked at me like I came from a different planet! Most likely because, as mentioned above, are just not a statiscally significant cause of car accidents.





Only some of us

Me? I'm all about safety. I just don't think that a few millimeters variance from original size is much of an issue, that's all. You don't have to be a slave to factory specification to be safe.



I answer tire questions all the time. I'm not at all educated but I'm reasonably well informed. If you catch me throwing caution to the wind you can whip me with a wet noodle!




Cheers
DD

 

If you want to match tire sizes I use this site Visual Tyre Size Calculator | Kouki Tech
It has helped me get a few of my car speedometer accurate with the jag they don't make the size I would need to make it accurate but I did get it from 8 k,s to 6 when it needed new tyres

Some Holden rims will fit but the offset is usually wrong and makes them snap studs just look at the scrap yards and the ones that are smashed usually have Holden rims on them that being said a good wheel shop can drill out the centerbore if its to small and change offset just gets expensive

there are a couple Australian wheel manufacturer's that make a few models for jaguars when I had My XJ 40 it had metric wheels on it I was ofered a choice of 15 16 or 17 inch diemeter rims I went with 16X7 and fitted yokohama Cdrive 215/60/16,s on it drove very nice

My XJR6 I went down from 255/45/17,s to 235/50/17,s transformed the car allows for instant over-steer if needed rides like a Jaguar should and gone is the dreaded XJR6 tram-lining which actually made the car dangerous