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Thread: Tyre sizes

  1. #11
    Senior Member Peterv's Avatar
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    Quote Originally Posted by Jimbov8 View Post
    Actually, his wheels are Kalimnos not Sentas.
    Ooops, my mistake!
    Sorry.

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  3. #12
    Senior Member Neilr's Avatar
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    The standard width was 285 mm. Most manufacturers use narrow wheels and a 285 tyre on a 9.5" rim seems borderline anyway and 295 mm seems to be over the commonly stated guidance for a 9.5" rim. 295 was originally the size selected for the XKR-S which probably has wider wheels.

    Some people have used the 295 mm tyre as an upgrade (as wider must be better, right?) but it does not seem to be the technically correct size for the standard sized rear rim. Doesn't the handbook mention the correct tyre sizes?
    S-Type 3.0 Manual MY2001 in Pacific Blue with Cashmere Leather Sport Seats, Sunroof, Melbourne Alloys, Premium Sound plus some other stuff ... 55k miles.
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  4. #13
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    try looking the tyre pressure sticker on the passenger door

  5. #14
    Senior Member Peterv's Avatar
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    Quote Originally Posted by Peterv View Post
    Ooops, my mistake!
    Sorry.
    and they do look better then my Senta's now that I took a good look, me want!
    There is no substitute for cubic inches!

    Jaguar XK 4.2 2006

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  7. #15
    Senior Member 8bit's Avatar
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    @bigbluemarine, MarkyM is correct, that design is called Kalimnos. It is very similar to the Senta design from the 4.2 cars though.

    Some wheel designs are slightly wider at the rear - the Vortex wheels (certainly the version from the 4.2 XKR-S, not sure about the version for the 5.0 cars) are 10.5J at the rear and are supplied with a 295 section tyre as standard. Kalimnos rears in the correct size for an XK/XKR are 9.5J so would have had a 285 section tyre from the factory, I gather.

    As Neil says the handbook should tell you the manufacturer stated sizes. Personally I wouldn't deviate from this, I've read stories of insurance claims being refused because tyres which are not of the manufacturer's stated size and load rating for the car was fitted. Will a 295 section tyre on a wheel designed for 285 actually have any performance or safety difference? Probably very, very marginal at best, assuming identical make and model of tyre in each size. You'll probably read people saying "I upgraded to 295 section tyres, I have way more grip now", what they won't be considering will be that the old tyres are probably shot and possibly also a poorer make and model.

    One other thing; if you fit a wider tyre with the same profile and rim size it will actually be wider and have a greater rolling circumference as the profile is expressed as a percentage of the section width, e.g. 30% of 295 is (slightly) greater than 30% of 285. Probably not enough to upset stuff like traction control, wheel speed monitoring etc. but the car will be configured for the fitted size of wheels and tyres from the factory.
    Current: 2009 XKR 5.0
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  8. #16
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    Wow, lots of info!
    Thank you everyone on this.
    8Bit/Neilr, you are absolutely correct, just checked through the manual and it states 285/30 R20 so at some point the wrong size were indeed fitted
    I intend to change all 4 tyres in the very near future so I will bear that in mind,

    Really appreciate all your feedback

    Jeff

  9. #17
    Senior Member Jimbov8's Avatar
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    May be worth checking the actual width of the rear wheel before you get the new rubber.
    Jim.
    2012 XKR Black pack, Speed Pack, Aero pack, Rat pack. Past:-87'XJS 3.6L, 93'XJ40 3.2L gold, 95'XJ6 4.0L sport, 00'XJ8 3.2L sport, 2005 XK8 4.2L coupe, 2009 XK 5.0L Portfolio in that order and enjoyed all of 'em.

    I do not offer advice, I only say what I would do with the set of circumstances presented. Your choice always.

  10. #18
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    Thanks JimbV8, I'll do that!

    Jeff

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  12. #19
    Senior Member 8bit's Avatar
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    Quote Originally Posted by Jimbov8 View Post
    May be worth checking the actual width of the rear wheel before you get the new rubber.
    Definitely no harm in taking one off to check (will be printed inside on the back of one of the spokes probably) but I've never seen Kalimnos wheels in larger than 9.5J. You could stick a measuring tape through and check the width that way too, if you didn't want to take it off the car.
    Current: 2009 XKR 5.0
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  13. #20
    Senior Member joc64's Avatar
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    One of the wider wheels that takes the 295 tyre on 5.0L models was the Vulcan which I’ve put on my car.

    I changed them as the car came to me with Senta wheels fitted. It is important to note that 4.2 and 5.0 L cars have different rear wheel offsets so 4.2 wheels (like Sentas) stick out too far on 5.0L cars and can rub on the wheel arch.
    I really liked the look of the Sentas though, so have them in my garage still! I will get round to selling them soon.
    Current Car: 2011 XK 5.0

    Previous Cars:
    2002 X Type, 1967 MGB GT, 1982 Rover SD1 Vitesse, 1975 MGB, 1984 Mini 25, 1973 Mini
    2017 BMM 530e, 2014 BMW 328, 2010 Audi A5, 2009 VW Touareg, 2006 Audi A6, 2000 Land Rover Discovery, 1997 Merc C Class, 1993 Volvo 480

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