Replies to This Discussion

Permalink Reply by Mike Schwab on March 30, 2014 at 2:54pm

http://sheldonbrown.com/tires.html
Tire valve: Presta for Presta.  Some rims could be drilled out for Schrader or Dunlop valves.  Some rims require long valves and short valves don't come out far enough to be inflated.

Schrader (like car tires) or Dunlop rims can use either valve.  Using a Presta tube in a Schrader rim is possible with a rubber o-ring (grommet) to fill the gap.  The screw on ring is not enough.

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

The tire width is subtracted from the nominal tire outside diameter to result in the bead diameter (ISO size).  Tubes do stretch, so one tube does cover a range indicated on the box and the tube.  You can't use a 1 1/8 tube in a 2 inch tire.  I.E. 700C or 27 in can fit in each other, as long as the width is close.

Latex tires are lighter but loose air faster, requiring pumping daily.  Common on road bike tires.  MTB tire are butyl rubber and can last for a week.

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Permalink Reply by Hey! Bike Shop Guy on March 30, 2014 at 2:57pm

Bike tires are stupid when it comes to size.  There are, no joke, like 5 DIFFERENT diameters of 26" tire for example and many of them take different size tubes because bikes hate you.

So the tires you have are pretty common tire sizes but quick question is your 20" tire actually labeled 1 1/8 in a fraction or is really 1.125 on the label?  I ask because 406 ISO tires are usually listed in decimal sizes...

OK, so if we put aside getting REALLY complex with this your small wheel needs a 20x1.25 tube and the 26" (the one labeled 559) wheel needs a 26x1.0 tube in nominal sizes. 

Bike wheels and tires have a labeled size system which is not anywhere near as standard as people would like it to be.  For example, there is a 27" wheel which is a little larger in diameter than a 700c but you sometimes see a 700c wheel labeled as 28" even though it is smaller in diameter than a 27 and THE EXACT SAME as a 29.  There is also a 28 that is larger in diameter than the 27 and 29.

No, seriously, you read that right...

This page has some charts that help make sense of it.

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Permalink Reply by djm on March 30, 2014 at 6:10pm

Short answer:  28-406 — First number is the tire width in mm, second number is the tire bead diameter in mm (measured to the shoulder of the rim where the tire seats).  406mm is the common 20" BMX wheel size; 559mm is the  common 26" MTB wheel size.  As Mike and HBSG have noted, there are multiple tire / wheel size conventions so common names for tire sizes are nominal rather than precise measurements.

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Permalink Reply by Lisa Curcio on March 31, 2014 at 12:29am

From one who is really stupid--go to your favorite good LBS and ask them to help!  But you thought of that already and are trying to understand the arcane world of tire  and tube sizes.

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Permalink Reply by Gene Tenner on March 31, 2014 at 3:03am

This is written on the tire: Continental 28-406 (20x1 1/8)
 
Hey! Bike Shop Guy said:

So the tires you have are pretty common tire sizes but quick question is your 20" tire actually labeled 1 1/8 in a fraction or is really 1.125 on the label?

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Permalink Reply by Hey! Bike Shop Guy on March 31, 2014 at 3:45am

Well this is all just wrong.

Yes you can drill out a rum but I think it is not a good idea; presta valves are superior to schrader so why would you bother?

ISO is the bead seat diameter and it is always going to be that regardless of the tire width and nominal size; ALL 700 wheels are 622 ISO and all modern mountain 26" wheels are 559 and on down the line.

Mike Schwab said:

http://sheldonbrown.com/tires.html
Tire valve: Presta for Presta.  Some rims could be drilled out for Schrader or Dunlop valves.  Some rims require long valves and short valves don't come out far enough to be inflated.

Schrader (like car tires) or Dunlop rims can use either valve.  Using a Presta tube in a Schrader rim is possible with a rubber o-ring (grommet) to fill the gap.  The screw on ring is not enough.

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

The tire width is subtracted from the nominal tire outside diameter to result in the bead diameter (ISO size).  Tubes do stretch, so one tube does cover a range indicated on the box and the tube.  You can't use a 1 1/8 tube in a 2 inch tire.  I.E. 700C or 27 in can fit in each other, as long as the width is close.

Latex tires are lighter but loose air faster, requiring pumping daily.  Common on road bike tires.  MTB tire are butyl rubber and can last for a week.

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Permalink Reply by Jerry Lee on March 31, 2014 at 11:38am

Gene;

   the 28-406 tire.. are you sure it is 406? 20 x 1 1/8 is a 451 tire.

the 20" tire come in 2 ISO sizes   406 for BMX and 451 for recumbents, rather for higher speed bikes. I believe most of your tire comes in 2 ISO sizes. ther are 2 sizes for 16", 20", 24" and 26". I don't think there are 2 for the 700 size, unless you compare 27" and 700.

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Permalink Reply by Gene Tenner on March 31, 2014 at 3:56pm

Yup. 406 it is. The bike is a used 2004 Burley Taiko, so I assume a 10-year old bike might have tires that are no longer in production. The shop I bought it from recommends (I got an email back tonight) 1.0 tubes for he 20 and 26 tires.

Jerry Lee said:

Gene;

   the 28-406 tire.. are you sure it is 406? 20 x 1 1/8 is a 451 tire.

the 20" tire come in 2 ISO sizes   406 for BMX and 451 for recumbents, rather for higher speed bikes. I believe most of your tire comes in 2 ISO sizes. ther are 2 sizes for 16", 20", 24" and 26". I don't think there are 2 for the 700 size, unless you compare 27" and 700.

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Permalink Reply by djm on March 31, 2014 at 5:57pm

Continental currently produces 406 tires but contrary to the usual convention where 406mm ISO wheel width is labeled in decimal inches to differentiate it from 451mm ISO, Continental seems to label 28-406 as "20 x 1 1/8" and 37-406 as "20 x 1 3/8".

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