How to calculate the correct tyre size when upgrading or downgrading your wheel size?
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.
August 14, 2009 @ 4:09 pm
Nice one paul
August 14, 2009 @ 4:11 pm
best !!!
August 14, 2009 @ 4:11 pm
wonderfull !
August 14, 2009 @ 4:41 pm
I usually go to this site to check tyre sizes
http://www.miata.net/garage/tirecalc.html
Instead of Flash it uses Java.
August 14, 2009 @ 5:34 pm
how to measure the rolling radius? how come diameter is alot smaller than radius? pls clarify
August 14, 2009 @ 5:44 pm
try this site
http://www.1010tires.com/tiresizecalculator.asp
August 14, 2009 @ 6:40 pm
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
August 14, 2009 @ 6:52 pm
How to use this application, cannot click on anything.
August 14, 2009 @ 7:51 pm
rolling radius is circumference, not diameter.
August 14, 2009 @ 10:01 pm
try this..
http://www.wheelsmaster.com/rt_specs.jsp
August 14, 2009 @ 11:06 pm
http://www.1010tires.com/TireSizeCalculator.asp
My regular tire size calculator
August 15, 2009 @ 12:23 am
no need to click .just choose all the number given
August 15, 2009 @ 1:18 am
http://www.wheelsmaster.com/rt_specs.jsp
What about this 1.
August 15, 2009 @ 1:31 am
yipeee~~
for my case:
from 175/70/13
to 195/50/15 only 0.1% difference
August 15, 2009 @ 8:59 am
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
August 15, 2009 @ 10:24 am
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
August 15, 2009 @ 10:30 am
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..
August 15, 2009 @ 1:50 pm
http://www.rims-n-tires.com/rt_specs.jsp is the most complete online calculator in this tire size comparison I’ve seen.
August 16, 2009 @ 9:28 pm
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-wishlist
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.
August 16, 2009 @ 10:20 pm
tyre circumfrace.
gearbox ratios.
with calculations, this data enebles you to find speed of the car in relation to rpm.
August 17, 2009 @ 2:15 am
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