OS Wheel sizes question

[mivvi]

My Araya's have 20 x 175 written on them but don't measure 1 and 3/4" wide, am I missing something here? I take it the measurement is in inches? 

[RATTY]

I think it refers to the tyre size, i stand to be corrected though

[theRuler]

bmx wheel measurement is bobbins

[Frosty]

yup I agree with Ruler, you can lay a 20x 1 3/8th rim over a 20 x 1.75!

So I think that Ratty's theory is right, tyre size

[mivvi]

So your saying a 20x 1 3/8th rim is wider than a 20 x 1.75 rim?

[Frosty]

diameter is bigger!

[Sanmarcopizza]

Does this help any ?

http://sheldonbrown.com/tire-sizing.html

[mivvi]

No Way!!! That's crazy talk?                20" is .....well....20"        or your tyres would fall off.

Anyhow, do I have an answer to: Is a 20x1 3/8 (Rim) wider or narrower than a 20x1.75 (Rim).

[Nosnod]

A 20x1 3/8 rim is narrower than a 20x1.75

However a 20x1.3/8 rim is larger in diameter than the 20x1.75 due to the 20 inches being the diameter when the tyre is on - as the 1.75 tyres are a lot deeper than a 1.3/8

I think this is right and hope it clarifies things 

[Frosty]

Head, nail hit it you have

[mivvi]

Ah, that's is now clearer. Its a crazy world of tyre sizes and I wish to never go there again.

Thank you all for your help and San for the link! 

[steve]

a 20 by 1.75 rim is 406mm actually 16 inches

a 20 by 1.3/8 and a 1.1/8 is 451mm 17 and three quarter inces

a sew up is 395 -15 inches inside and 432 =17inches outside


-its all about the added tyre profile to get to 20 inches

-stcik to the etro sizes

the funny thing is, that they fit bigger wheels to mini's and micro's, which i think is hilarious
 

although a 20 by 1.3, is the same rolling radius -with the tyre on, as a sew up

a 406 by 28mm etro tyre is a half inch smaller

-the 400 by 25 on the new redline micro, even smaller