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Tyre size and speedo.

AndyMc.....
AndyMc..... Posts: 3,248 Forumite
1,000 Posts Combo Breaker
Changing from 195 45 R16 to 175 65 R14, will there be any effect on the speedo readings?

Comments

  • facade
    facade Posts: 7,970 Forumite
    Part of the Furniture 1,000 Posts Name Dropper
    No they are within 0.4% circumference when they are new, it will change a lot more than that as they wear.


    https://tiresize.com/calculator/
    I want to go back to The Olden Days, when every single thing that I can think of was better.....

    (except air quality and Medical Science ;))
  • AndyMc.....
    AndyMc..... Posts: 3,248 Forumite
    1,000 Posts Combo Breaker
    facade wrote: »
    No they are within 0.4% circumference when they are new, it will change a lot more than that as they wear.


    https://tiresize.com/calculator/

    A uk site puts it at 0.2%

    https://www.oponeo.co.uk/advice-and-tips/tyre-size-calculator/195-45-r16#alternativeTireTool

    The handbook has both sizes listed so surely there’s only one speedo across the board.
  • Gloomendoom
    Gloomendoom Posts: 16,551 Forumite
    Part of the Furniture 10,000 Posts Combo Breaker
    A uk site puts it at 0.2%

    https://www.oponeo.co.uk/advice-and-tips/tyre-size-calculator/195-45-r16#alternativeTireTool

    The handbook has both sizes listed so surely there’s only one speedo across the board.

    Very likely. 0.2% is negligible and will be within the required accuracy range.

    Land Rover used to fit two different speedos to cope with small and large tyre options.
  • AndyMc.....
    AndyMc..... Posts: 3,248 Forumite
    1,000 Posts Combo Breaker
    Very likely. 0.2% is negligible and will be within the required accuracy range.

    Land Rover used to fit two different speedos to cope with small and large tyre options.

    It’s not a Land Rover and a cant imagine ford doing it. Would it over or under read?
  • Gloomendoom
    Gloomendoom Posts: 16,551 Forumite
    Part of the Furniture 10,000 Posts Combo Breaker
    It!!!8217;s not a Land Rover and a cant imagine ford doing it. Would it over or under read?

    According to that first link the 175 tyres will rotate 879 times in a mile and the 195 tyres 881.

    With the 175s the speedo will read slightly slower than with the 195s but the difference is so tiny that it can be ignored.
  • forgotmyname
    forgotmyname Posts: 33,023 Forumite
    Part of the Furniture 10,000 Posts Name Dropper
    It will underread by a gnats left whisker. But as the speedo probably overreads anyway you maybe closer to the true figure.

    Will the 14" wheel fit over the brakes? Didnt have 16" wheels to fit over better brakes?
    Censorship Reigns Supreme in Troll City...

  • AndyMc.....
    AndyMc..... Posts: 3,248 Forumite
    1,000 Posts Combo Breaker
    It will underread by a gnats left whisker. But as the speedo probably overreads anyway you maybe closer to the true figure.

    Will the 14" wheel fit over the brakes? Didnt have 16" wheels to fit over better brakes?


    Yeah it fits the spare is a 14” steel rim and fits fine although it has a space saver sticker as it’s a different size wheel.

    No better brakes just oversized alloys that haven’t stood up to uk roads.
  • AndyPix
    AndyPix Posts: 4,847 Forumite
    Fifth Anniversary 1,000 Posts Name Dropper Photogenic
    I think guys with large tyre size should be banned from wearing speedos
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