#1 2012-03-28 07:23:44

savanni
Member
From: Austin
Registered: 2011-04-30
Posts: 82
Website

Tire size mismatches

Okay, I have two bikes here.  On one of them I'm trying to replace a flat tube and have discovered that there is no amount of force I can apply to get the tire back on.  In the midst of this I've discovered some mysteries that I'd like to clear up.

Both bikes have, on the front wheel, a 20 x 1 1/3 tire.  Thing is, even a casual visual inspection reveals that the front wheels are not the same size.  One measures 18 1/3 inches across, the other measures 16 1/3 inches across.  But the tires have the same numbers on them: size 20 x 1 1/3.  They're made by different manufacturers.  And, it's the small one, the 16 1/3 inch rim, that I can't get the tire back onto.  What's more, the 20 x 1 1/3 tube that I put into the tire is actually folded up within the tire!

What gives here?

If I can figure out the size of the rim, how do I ensure that I'm buying a replacement tire that fits easily?  One way or another I'm going to have to special order this thing, and the previous owner put a mylar coating on the rim that completely destroyed any labels that may have been there.

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#2 2012-03-28 07:52:41

savanni
Member
From: Austin
Registered: 2011-04-30
Posts: 82
Website

Re: Tire size mismatches

Okay, I was able to do some more research.  I discovered that, assuming the original company did not change wheel sizes between models, that the official wheel size for the bike I'm having trouble with is '20" ETRTO 406'.  Still a very mysterious number, but the other wheel is 20-451.  So, "size 20 x 1 1/3" remains a mystery.

Last edited by savanni (2012-03-28 07:53:59)

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#3 2012-03-28 08:26:39

CharlesDuffy
Member
Registered: 2009-07-03
Posts: 56

Re: Tire size mismatches

savanni wrote:

If I can figure out the size of the rim, how do I ensure that I'm buying a replacement tire that fits easily?  One way or another I'm going to have to special order this thing, and the previous owner put a mylar coating on the rim that completely destroyed any labels that may have been there.

When it comes to needing to special-order odd-sized tires --

Have you checked Mike Librik's shop, Easy Street Recumbents (behind the Goodwill on Lamar)? I actually ride a folder, not a 'bent, but as it uses 16"x1 3/8 wheels, they're the only place I can find properly sized tires and tubes in stock locally. He certainly carries plenty in 20" as well.

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#4 2012-03-28 09:21:06

savanni
Member
From: Austin
Registered: 2011-04-30
Posts: 82
Website

Re: Tire size mismatches

I haven't talked to him yet because it was early this morning that I figured out that this doesn't fit well.  I've gotten tires and tubes from him before.  Just looking for a way to get a replacement without needing to take the gear into him since I'm trying to live without depending on a car (and come September I'm even completely eliminating that choice) and he's around 17 miles away from me.

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#5 2012-03-28 11:40:09

foolmanchoo
Member
From: 04
Registered: 2008-11-26
Posts: 8
Website

Re: Tire size mismatches

What kind of bike is it? Just curious.

CharlesDuffy is correct on the Easy Street recc... all kinds of abnormal tubes and tires there.
The best thing for you is to simply be prepared. Tubes are not that expensive, even the odd sizes... so just buy a bunch for backup.
And you can always order online if can't find what you're looking for. I have a fleet of folding bikes I keep roadworthy for my guests and my test riding... keeping stock is your best bet.

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#6 2012-04-04 10:40:44

savanni
Member
From: Austin
Registered: 2011-04-30
Posts: 82
Website

Re: Tire size mismatches

The bike's a Challenge Hurricane.  The model that looks like http://www.ligfietswinkel.nl/images/sto … ack_bs.jpg but with a better rack on the back .  Their new model has a different shape for the fork that mounts the rear tire and is probably a little friendlier to panniers than this model.

End result, I took the rims up to Easy Street to talk to Mike.  We found another tire, Kojack brand, of theoretically the same size (20" x 1.35", 35-406) and tubes of the correct size (406, again).  He proceeded to put the tire on by hand.  I still needed to use a tool, but I didn't need to try very hard.  A little difficulty getting the bead set in the rim, but not a whole lot.  I've done about 40 miles on them now and they do the job nicely.  I'm slightly skittish about being on tires this slick, but it doesn't seem to make much difference, and I handled a curve at 33mph just fine this morning.

Last edited by savanni (2012-04-04 10:44:58)

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#7 2012-04-05 23:44:50

dougmc
Administrator
Registered: 2008-06-01
Posts: 620

Re: Tire size mismatches

savanni wrote:

I'm slightly skittish about being on tires this slick, but it doesn't seem to make much difference, and I handled a curve at 33mph just fine this morning.

By slick, do you mean "not having a tread pattern" ?

If so, it makes no difference -- in fact, on a bike (where the wheel cross section is round) slicks get better traction on dry *or wet* pavement than similar tires with a tread pattern.

Here's a citation if you want to read more on it.

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