Hello,
I expect to be picking up a 2009 XKR next month. It comes without a spare wheel, just the repair kit, which worries me.

It has 20" OEM wheels. My research on this excellent forum shows that there are no 20" spare wheels avalable, only 19" and 18", in 135/70-19 and 135/80-18 respectively. I have gathered that for a 20" it is recommended to use the 19" spare wheel. However assuming I manage to buy a complete XK kit (the sparewheel plus the plastic tray that fits inside it containing the jack etc) it will of necessity date from 2006 to 2014, and will be too old to safely use the tyre. I've been unable to find any brand new 135/70-19 tyres for sale here in France. On the other hand new 135/80-18 tyres are readily available. The 135/70-19 and 135/80-18 have virtually the same diameter., so that's no problem.

All of which to lead up to my two questions. Is there any reason not to use a 135/80-18? And have there been any changes to the spare wheels over the years, such that I would have to make sure I bought a spare wheel before or after a certain date?

Many thanks for your help and advice.
Tony

 

Does the XKR in question have the 4.2 or 5.0 V8?
I ask because AFAIK 2009 was the change over from the 4.2 to the 5.0, and the 4.2 came with 355 mm front brakes while the 5.0 came with 380 mm front brakes.
The 18" space saver spare will fit over the 355 mm front brake calipers but it will not fit over the 380 mm front brake calipers, while the 19" space saver will fit over both.

 

Many thanks for your rapid reply. It's the 5 litre version, so it sounds like I'm stuck with the 19" spare wheel - and a very old tyre...
Thanks again
Tony

 

my old 19" spare delaminated when I needed it, it had never been used, of course it was 13 years old. I would certainly keep looking for a new replacement.
wj

 

Yes, that's precisely what worries me. Don't know what I can do about it though. Any spare wheel I manage to buy will date from 2066 to 2014, so at best the tyre will be 10 years old.
Any suggestions, anyone?
Thanks
Tony

 

That reminds me. So has mine. Need to get a replacement tire....

 

Hello again
I've been worrying about using such an old tyre on the spare wheel, so I did a search on different spare wheel tyre sizes. I came up trumps with 125/70 19 - available with a decent make (Continental).
So the question is would there be any problem fitting that size tyre to the rim? Or any other issue ?
Tony

 

A 125 will have about 7.5% less rolling diameter than a 135 which may be enough to upset one or more sensors and cause them to throw DTCs, but I'm only guessing.
These space saver spare tyres all have a max speed rating of 50 mph / 80 km/h so as long as you take it easy and go as slowly as you safely can (ie not to cause a problem for other motorists) it should be OK to limp the car home or to a tyre shop whichever is closer.

 

Thank you for your reply. I was very surprised by your 7.5% less rolling diameter. According to the tyre calculator sites, the difference (135/70 19 versus 125/70 19) is only 2.08%, which I can't see as being much of an issue. What do you think?

 

You are correct and I got it wrong!
My tyre size calculator gives 1.9% so even less than yours and yes so little difference as to not be an issue.

 

Thanks again for your rapid reply.
So no problem with the tyre size. My other worry was whether a 125 would go on the rim OK.
What do you think please ?

 

Won't be a problem as both the 18" and 19" versions are the same rim width, 4 inches, and 125 is only a measly 10 mm less than 135.

 

Many thanks. So now I can buy an old 19" spare wheel in the knowledge that I can buy a brand new tyre to replace the old one.
As many, if not most, XK's supplied in France (where I live) were supplied without a spare it may be some time before I find the full kit (spare wheel + the jack-kit).
I'll probably want to be certain (as in I've driven it home) that I've got my XKR before I buy the spare wheel. I'm not expecting to get the XKR until mid-June.
I will, of course, let you all know how I get on.
Thanks again
Tony