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Change of tyre size

Discussion in 'General Cars' started by jamesdean1986, 26 Sep 2017.

  1. jamesdean1986

    jamesdean1986

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    My VW Passat is currently running on 235/45/r17 but some excellent tyres have come up a great price but they are 225/45/17.
    I'm fairly sure they will be fine to be fitted but wanted other people's thoughts to be safe as the speed and load are slightly lower at 97Y vs 94W.
     
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  3. Mottie

    Mottie

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    Shouldn’t be too much difference but may make your speedo read slightly different. Depending on the rim size, the tyres may look slightly stretched on the rim being 10mm narrower. The '45' in the size represents a sidewall height of 45% of the '235' mm tyre width which is approximately 4mm taller than a 45% profile on a 225 tyre. Speed and load shouldn’t be a problem - load is irrelevant on a passenger car and the speed rating is faster than your car could possibly achieve.

    You can check the difference here: http://www.willtheyfit.com/
     
    Last edited: 26 Sep 2017
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  4. freddiemercurystwin

    freddiemercurystwin

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    But if changing size you must always have the same size on each axle.
     
  5. Mottie

    Mottie

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    Good point. As an MOT tester, I should have thought of that! I just assumed the OP was looking at a set of 4. Assumption - the mother of all **** ups!
     
  6. DaveHerns

    DaveHerns

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    You need to tell your insurance company .
     
  7. jamesdean1986

    jamesdean1986

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    Budget wise I was only looking for two as they are normally £120 each for the normal size. But the 225s have halved in price so can get 4. Didn't think there would be an issue but just needed to check
     
  8. Astra99

    Astra99

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    I wrote a program to compare the differences between two different sizes of tyres. I have input your tyre details, and (hopefully) attach the results. 235-to-225x45x17.png
     
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  9. Uh, why. An insurance company will ask if your car has been modified, because they assume you are trying to improve it's performace, but putting on a tyre that will make the car go slower, isn't really an issue.
     
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  11. DaveHerns

    DaveHerns

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    Because it's a deviation from manufacturer's spec and therefore counts as a modification and not one done as an improvement. They could reject any claim as a consequence. That's how insurers work these days.
     
  12. But by that reasinign, you could argue that you have to replace the tyres with the same make. I'll agree with the definition of deviation from the manufacturers spec, but if there's no flexibility on a very minor channge of tyre, then it's getting pretty crazy.

    I'd agree with changing the rims to accomodate a different size of tyre, but I think common sense should allow a 10mm difference.
     
  13. Burnerman

    Burnerman

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    I don't think there would be any problem with this at all.....the fitting of winter tyres et al has been discussed at length here and I'm sure there is a 10 - 20% margin in rim widths.
    www.oponeo.co.uk
    John :)
     
  14. Mottie

    Mottie

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    What Golf is it anyway? I’ve just stuck a set on my daughters Golf and they were only H rated tyres. I don’t think many Golfs come with Y or W rated tyres as standard fitment.

    Edit. I see it’s a Passat. What model though?
     
  15. DaveHerns

    DaveHerns

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    We aren't talking common sense here, we are considering insurers and their attitude on undeclared modifications. I wouldn't risk fitting the "wrong" tyres but it's your choice.
     
  16. Avocet

    Avocet

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    They wanted to know when I fitted a tow bar, so they'd certainly be interested in tyres! Is the OP intending to fit tyres of the same load and speed rating as original equipment, even though they're not the same size?
     
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