XJS tyres

[steve_m]

Hi. I've just bought a 1986 XJSC (V12) and it is running on slightly wider rims than usual, namely 15" x 7" and running very old Nanking 235 x 60 x 15 tyres.
The tyres look over profiled to me so I was wondering if anyone has any experience of a suitable tyre for these sized rims?
Ta, Steve.

[dhdove]

Hi Steve

If you use the search option at the top of the main XJS BB page and enter tyres you will find much useful information on this subject.
If your query isn't answered there post back here and I'm sure someone can help.
I can tell you that all 15" tyre profiles are becoming increasingly hard to come by which is why some members have upgraded to 16" wheels, these usually available from eBay etc.

Do let us all know how you get on

Best
TonyS

[steve_m]

Thanks Tony. I've had a good scour through the forums but can't find anything specific. I've also searched loads of tyre suppliers but no luck so far; I've e-mailed Micheldever Tyres which are our local gurus so will wait for a reply from them.
I don't want to go to the expense of buying new wheels as I've only just bought the car and they are the best thing on it at the moment!
I think that they are slightly oversized at 7" rims because they foul the arches on full lock when reversing which can't be right.
If I can't source the original spec tyres is there a different width/profile that would fit?
Steve

[CliveRothwell]

235x60x15 is one of the preferred sizes in the Jaguar Owners Handbook so what you have is certainly correct. Pirelli specifically made the P600 for the XJS. It is on back order at present (well, was back in Sept 2011 when I was looking for some). This means that stockist will take your order and when Pirelli feel they have enough orders, they will make a batch and send them out to the appropriate suppliers. If you have subsequently sourced a tyre elsewhere, nobody will force you to part with your money given that the tyres ARE in short supply. I rang around for two days before tracking 2 down at Kwik Fit for £150 fitted each. Going up to a different size does alter the rolling radius of the tyre and will have a minor effect on the odometer, ABS and trip computer. The shelf life for tyres is 5 years should you happen to find some on ebay and can be dated using the date code on the tyre wall. Hope this helps - good luck.

Clive

[poprivet]

Steve, It sounds like you have the wrong alloys for your car, perhaps the offset is incorrect. They should have a part number on them, if you post that here it should be possible to see what car they were designed for originally.

They could be correct 'later' xjs wheels, but these were only one part of a sportspack suspension upgrade and can cause problems as you describe.

[steve_m]

Thanks for the info guys.
I am guessing that the wheels aren't original given the 7" rims, shouldn't they be 5 1/2" or similar?
The car has a few odd details, apparently uprated suspension (it corners very flat), allegedly factory fitted Recaro seats and Momo steering wheel and a grey and green trim that I have not come across before.
There is also the tuning extra of a small petrol filter fitted to the end of the vacuum advance tube as opposed to it being fitted to the intake manifold; I guess that means the advance is in a slightly non-working mode.
As a matter of interest how would different sized tyres affect the ABS?
Steve

[BigCatXJS]

The Jaguar Lattice 15" is 6.5J whereas your wheels are 15" / 7J?

You can upgrade to 16" (though 16" lattice is very rare) as this would bring a slightly firmer ride with better handling - a good trade-off, although migrating back to the standard Jaguar Lattice 15" might be cheaper / easier? Plenty of used and refurbished lattice 15" around...

In terms of tyres - good luck with getting a P600! You might want to consider 225/60/R15 96W instead of 235/60/R15; still plenty of tyres available in this size (Falken ZE912 is a good, reasonably priced option) and only a 2mph per 100 mph difference on the speedo.

You might want to look at the Free Tyre calculator / size guide link on this page;
http://www.kwecars.com/jaguar/tech-centre/index.php

Can't think of a reason why your ABS would be compromised by a different tyre or wheel size.

Thanks, Rich

[steve_m]

Thanks Rich
I only questioned the ABS because Clive mentioned it in his reply; I can't see any reason myself either.
I realise that going to 16" wheels is the easy way out but having just got the car I've plenty of other things to spend my hard earned on (having to sell a kidney to get the rear window replaced to start with) and the (lattice) wheels are in exceptionally good condition.
I'll have a hunt around for the 225 profile ones which may also ease the wheelarch rubbing problem.
Steve

[555ttg]

Somebody else mentioned offset here.
It could be that you have Lattice wheels from an XJ40 which were, I believe, 7J.
The offsets for the alloys were different, and if you fit XJ40 alloys the front wheels will "rub" on full lock either in forward or reverse,(you also mentioned this above).
Check with some of the more knowledgeable guys here, but if I remember correctly, the offsets for the XJS were 19mm front, and 33mm rear, whereas the XJ40 alloys, are all 33mm, hence the rubbing and fouling.
So in summary, it maybe that the width of the wheels are OK, but the offset is wrong for the fronts.
I have had it happen to me with SPEEDLINE wheels from XJR XJ40s and trying to fit them to TWR XJSs.
Let me know how you get on, as the automatic posting of topics updates, is still not working.
Phil

[poprivet]

Some further thoughts, I think in 1986 the xj-s would be on 6.5" x 15" starfish wheels with 215/70x15 tyres? I'm sure Brian our cabriolet guru would know for certain. The offsets were the same front and rear except on TWR and other highly specialised versions.

Also I thought ABS only came in with sportspack in 1987, or was there a system before the Teves.

I would advise finding out exactly what all the previous owners 'modifications' were before splashing out on a set of tyres that may not fit those wide rims and also not cure the rubbing problem.

[dhdove]

Steve

If you're feeling adventurous you could take some pics of the wheels and post them here. It can be a bit of a trial at first but once you grasp it it's pretty straightforward, i recently posted a guide for another member on the XK8 BulletinBoard, so you could take a look at that.
We can then try to id exactly what you have fitted to your car and go from there, any markings on the wheels please post a close-up. I have pics of all the wheels fitted to the XJS which formed the basis of a mag article a couple of years ago so I'm sure between us that we can arrive at a diagnosis at least if not a solution

Best
TonyS

[steve_m]

Ok folks, thanks for all the input. I'm messing about on boats at the moment but I'll have a good look at the weekend.
Incidentally the tyres don't rub when going forward, only when reversing: I came across the same problem somewhere in the forums but can't find it again.
My previous (non factory) Cabriolet had the lattice alloys on too, made by Fondmetal as I recall but I don't recall any problems with that one.
225/60/15s seem to be readily available so I will probably go down that route as long as they physically fit the rims correctly. I'm only going through all this because the front offside has a very nasty split in the sidewall.
Mind you I'm gleaning lots of other useful information whilst trolling through the forums and the internet.
Next job is to clean all the fuse holders as a lot of the electrics operate at random; ALDI are doing a set of 'sonic cleaners' which are basically different sized electric tooth brushes with stiff bristles and look ideal for getting in all those little nooks and crannies.
Steve

[CliveRothwell]

My error chaps - ABS probably would not be fitted to this car!

[steve_m]

I don't recall seeing an ABS accumulator or dashboard warning light so I guess that it is not fitted.
It does have non-working cruise control though.
I seem to remember reading somewhere a while ago that somebody (Brian?) was compiling a Cabriolet register; is it accessible through the forums?
Steve

[PaulGover]

...
There is also the tuning extra of a small petrol filter fitted to the end of the vacuum advance tube as opposed to it being fitted to the intake manifold; I guess that means the advance is in a slightly non-working mode.
...

If that filter is tied to the LH wing brace, I think it's more likely to be an air filter for the air feed to the distributor. There V12 distributor has a very hard life, and one of Jaguar's fixes was to put an air bleed into the distibutor; I'm not sure if that was for cooling or to prevent condensation, or to prevent the dizzy living in engine fumes. Whatever, AFAIK, that pipe's nothing to do with vacuum advance; the engine management system handles the advance, not the dizzy.