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Guest Message by DevFuse
 

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Why I think tire size calculators are for the birds.


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9 replies to this topic

#1 ezapar

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Posted 09 April 2007 - 10:34 AM

Cuz tire sizes vary too much from manufacturer to manufacturer, that's why.


Two tires in the photos are marked "27". One is marked 8.5, one 9.5 for width. The swamper is at least an inch taller an probably 2 inches wider.


Posted Image

For reference, left to right: 27/9.50/14, 225/55/17, 27/8.50/14, 205/60/15, 175r14.
Posted Image

#2 nipper

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Posted 09 April 2007 - 10:37 AM

You need to know the sidewall size. Tire calculators only work for std sizes. Now with so many differnt sidewall sizes, you can throw them out the window.

Tires of the same brand make and model can vary somewhat from lot to lot too.

nipper

#3 Andyjo

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Posted 09 April 2007 - 11:06 AM

Nice comparison... but Zap.. you have way to many tires... almost as many as me :-p

#4 Phizinza

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Posted 10 April 2007 - 07:18 PM

The Kumho's only have 7.75" of tread width.. :(

Love those swampers.. Just if they wren't 3 times the price of every other tire in Australia...

#5 baccaruda

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Posted 11 April 2007 - 01:43 AM

http://www.miata.net...e/tirecalc.html ?

Zap, what kind are those in the middle?

#6 Rooinater

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Posted 11 April 2007 - 04:30 AM

that's why you measure the actual std size then compute it...

#7 Phizinza

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Posted 11 April 2007 - 05:07 AM

Zap, what kind are those in the middle?

Kumho Venture M/T's I think you'll find..

#8 nipper

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Posted 11 April 2007 - 09:30 AM

13 14 15 refer to the wheel size. YOuy need to know the sidewall aspect ratio to get the proper numbers
http://www.tirerack....e.jsp?techid=46

Or just measure the cricumfrance of the tire :P

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#9 ezapar

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Posted 11 April 2007 - 11:07 AM

13 14 15 refer to the wheel size. YOuy need to know the sidewall aspect ratio to get the proper numbers
http://www.tirerack....e.jsp?techid=46

Or just measure the cricumfrance of the tire :P

nipper



You don't get what I'm getitng at. . .

I'm saying that tire sizes vary too much from tire to tire to get an accurate calculation. You would need to physically measure it.

#10 Phizinza

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Posted 11 April 2007 - 09:52 PM

13 14 15 refer to the wheel size. YOuy need to know the sidewall aspect ratio to get the proper numbers
http://www.tirerack....e.jsp?techid=46

Or just measure the cricumfrance of the tire :P

nipper

What we're saying here is a tire like the 27x8.5R14 Kumho Venture M/T isn't that size at all so looking at measurements means jack all...

It reality it measures 26.4x7.75R14.. And that Super Swamper looks more like a 27.5" not 27..

I have found on a lot of tire websites (in Aus at least) these days they give you a OD in mm, which is a much more currect size.. normaly.




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