How to calculate the correct tyre size when upgrading or downgrading your wheel size?

Advertisement

Tyre Size Calculator

I stumbled upon this really nifty utility on the internet. Kouki Tech has this really cool Flash-based utility where you can easily compare different tyre and wheel sizes both through hard numbers (end result of circumference, diameter, sidewall height) as well as visually see how different the tyre sizes will be. It’s very useful if you want to change to a tyre size that’s different from your car’s original size. The utility will also tell you how off your speedometer reading will be. Click the image above to access the Visual Tyre Size Calculator by Kouki Tech.


Related stories you might be interested in reading:


About the Author

After dabbling for years in the IT industry, Paul Tan initially began this site as a general blog covering various topics of personal interest. With an increasing number of readers paying rapt attention to the motoring stories, one thing led to another and the rest, as they say, is history. An avid electronic gadget aficionado as well as big-time coffee lover, he's also the executive producer of the Driven motoring TV programme.

Comments

  1. B33MER says:

    Nice one paul :)

    Reply Thumb up 0 Thumb down 0
  2. Simon says:

    best !!!

    Reply Thumb up 0 Thumb down 0
  3. Simon says:

    wonderfull !

    Reply Thumb up 0 Thumb down 0
  4. 2fast says:

    I usually go to this site to check tyre sizes

    http://www.miata.net/garage/tirecalc.html

    Instead of Flash it uses Java.

    Reply Thumb up 0 Thumb down 0
  5. tayamaster says:

    how to measure the rolling radius? how come diameter is alot smaller than radius? pls clarify

    Reply Thumb up 0 Thumb down 0
  6. Xoomie says:
    Reply Thumb up 0 Thumb down 0
  7. shan says:

    damn difficult to explain this to uncles and pa's about the importance of tire sizes…at the tire shops, once the rim size matches, its an all go…little do they take into account the profile, diameters and other relevant measurements…sigh

    Reply Thumb up 0 Thumb down 0
  8. acerman says:

    How to use this application, cannot click on anything.

    Reply Thumb up 0 Thumb down 0
  9. Paul Tan says:

    rolling radius is circumference, not diameter.

    Reply Thumb up 0 Thumb down 0
  10. shah333 says:
    Reply Thumb up 0 Thumb down 0
  11. DCRS says:

    http://www.1010tires.com/TireSizeCalculator.asp

    My regular tire size calculator

    Reply Thumb up 0 Thumb down 0
  12. mikasa says:

    no need to click .just choose all the number given

    Reply Thumb up 0 Thumb down 0
  13. DCRS says:
    Reply Thumb up 0 Thumb down 0
  14. bugger says:

    yipeee~~

    for my case:

    from 175/70/13

    to 195/50/15 only 0.1% difference ;)

    Reply Thumb up 0 Thumb down 0
  15. jonny blaze says:

    Rolling radius = radius of wheel + height of sidewall

    eg 205/50/16

    205 is width of tyre in millimeter

    50 is the profile or aspect ratio or height of the sidewall of the tyre and is expressed in percentage of width, 50% of 205 = 102.50mm

    16 is the diameter of the wheel in inches

    radius of wheel is 1/2 of its diameter, 16/2= 8 inches

    1 inch = 25.4mm

    8 inches = 25.4 x 8 = 203.20mm

    Therefore, rolling radius = 203.2 + 102.5 = 305.70mm

    Reply Thumb up 0 Thumb down 0
  16. jonny blaze says:

    Rolling radius = radius of wheel + height of tyre's sidewall

    eg 205/50/16

    205 is the width of the tyre in millimeters

    50 is the profile or aspect ratio or sidewall height, expressed in percentage of width,

    50% of 205 = 102.50mm

    16 is the diameter of the wheel in inches

    radius is 1/2 of diameter, 16/2 = 8 inches

    1 inch = 25.4mm,

    8 inches = 25.4 x 8 = 203.20mm

    Therefore, rolling radius = 203.2 + 102.5 = 305.70mm

    Reply Thumb up 0 Thumb down 0
  17. jonny blaze says:

    sorry for double post.

    my post didn't appear at when I checked at 10.24am, so I resubmitted my comment.

    and that is when the double appeared..

    Reply Thumb up 0 Thumb down 0
  18. ivan98 says:

    http://www.rims-n-tires.com/rt_specs.jsp is the most complete online calculator in this tire size comparison I've seen.

    Reply Thumb up 0 Thumb down 0
  19. Insomniac says:

    Hi,

    Just popped in to see where the sudden influx of traffic came from. Glad you like my wee utility, its basic compared to some but I was going for ease of use over masses of numbers. I'm currently developing V2 of the calculator as well as a visual wheel offset calculator.

    If anybody has an idea or suggestion for ways to improve the caculator then please feel free to leave a comment here:
    http://www.kouki.co.uk/tyre-size-calculator-v2-wi…

    PS, for those confused about the term "rolling radius", don't be. Its a daft term I picked up somewhere and probably only makes sense in my head. It is actually the circumference of the wheel & tyre combination.

    Reply Thumb up 0 Thumb down 0
  20. awak says:

    tyre circumfrace.

    gearbox ratios.

    with calculations, this data enebles you to find speed of the car in relation to rpm.

    Reply Thumb up 0 Thumb down 0
  21. armandd says:

    here's another one, complete with tyre width, offset, revs per mile, whether the new rim will hit the fender or not, other size suggestion etc etc…

    http://www.rims-n-tires.com/rt_specs.jsp

    Reply Thumb up 0 Thumb down 0

Like us? Show some support! :)




Leave a Comment

Want a picture next to your comment? Register for a Gravatar account with the same email you use to comment!

Previous Story: The new BMW ActiveHybrid X6 xDrive50i: world’s most powerful hybrid!
Next Story: Next-gen Audi MMI to feature handwriting input