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Actual tire diameter(8 posts)

Actual tire diametersacheson
Oct 4, 2002 5:54 AM
I have a question regarding the "actual" diameter of a road tire based on the theory that a 700 X 23 tire does not yield the same diameter tire from different manufacturers (I developed this theory from some older Specialized 700 X 23 road tires that were actually larger than my Conti 700 X 25s).

Presently, I am using Vittoria Rubino kevlar bead, 700 X 23 c tires on a CXP33 rim. I purchased a custom road frame wanting a short rear-end, and while putting it together last night I noticed 'less than ideal' clearance between the chain stay and tire.

Before I call the builder and discuss option with him (since everything else about the frame is absolutely perfect), I'd like to assess the tires I am using and see if I am able to increase the clearance while still using an advertised 700 X 23 c tire. Make sense?

So, in relation to a Vittoria Rubino, how do Continentals, higher end Vittorias, Hutchison, Michelin, Veloflex, Vresdein, etc. match up in diameter?

Thanks in advance.
re: Actual tire diameterpmf1
Oct 4, 2002 6:55 AM
Maybe you know this, but I didn't until a few years ago. The measurements given with tires are the height, not the width. Taller tires are usually a little wider, but not always.

You are indeed correct that all tires that are advertised to be 700x23 are not exactly the same size. I've never used Vittorias, but I find Michelin, Vreds and Hutchinson to be pretty similar. Contis run more narrow.

Just out of curiosity, what is a less than ideal clearance between the chainstay and the tire? Too close?
re: Actual tire diametersacheson
Oct 4, 2002 7:16 AM
"Less that ideal clearance" = too close ... correct. +/- 2mm on each side. I had an old 20 c tire that I put in. The clearance was ample ... but I'm a little reluctant to train on that narrow of a tire (I'm 180 lbs).
Conspiracy theorists speculate...filtersweep
Oct 4, 2002 8:08 AM
...tires are "mis sized" so companies can post lower weights for their tires... ie they are prone to run small.
Continentals run smallDougSloan
Oct 4, 2002 7:06 AM
I swear that nominal 23mm Continentals are equivalent to about a 21. A 25 Conti is more like a Michelin or Vittoria 23. Veloflexes are exactly the same as Vittorias, the full 23 or so.

Doug
Continentals run smallsacheson
Oct 4, 2002 7:17 AM
Thanks Doug. I'll look into a pair of Contis.
re: Actual tire diameterjw25
Oct 5, 2002 10:23 AM
Well, I've only used Rubino's at 20c (TT training), and they're pretty skinny, but the Open Corsa's I have are pretty fat for 23's, compared to most other "23c" tires I've run.
Michelin 23's are closer to 22mm wide on an Open Pro rim, as are Conti GP-3000's. Hutchinson Reflex Golds (a good trainer, and good enough to race, IMHO) are skinnier, measuring at 21.5mm (yes, I have calipers, and I'm not afraid to use them).
Pariba and Vredestein tend to run wider than advertised, with my 22c Pro-Criteriums at 24mm, and my 20c Pro-Prologues at 22mm. Great tires if you can find them, though.
A Vredestein Fortezza wasn't as bad, hitting just over 23mm, as I recall.
Haven't used a Veloflex yet, but since they're ex-Vittoria, they'll probably run wide.
Panaracer runs pretty true to size, as well.
I swore off Specialized's a long time ago, after some nasty experiences, but I think they ran true to size as well.
So, I'd recommend grabbing a measurement off the Vittoria, to see if it's the same as the Corsa's, and going from there. Michelin and Conti are probably your better bets, and both make good race rubber, with the Michelins winning in durability, for me at least.
Conti Ultra (skinwall): 22 mm wide/Conti GP3000 (gumwall): 23 mmMarkus_B
Oct 5, 2002 1:53 PM
both 700 x 23C with Ksyriums.

But I don't understand why you insist on an advertised 700 x 23C tire.

The way they run depends on the actual diameter/width - if you use a "wide" 20 or a "narrow" 23, what's the difference?

Anyway, I wouldn't like the tire to rub off the frame's coating and apply some durable self-adhesive tape (though this may cost another 0,5 mm of clearance).