The best way is to ask the iBOB list. Many there are semi-fanatical about mismarked tires, prefer fatter tires, and routinely measure them to determine actual vs. labeled widths.
Charles T. Young
<firstname.lastname@example.org> Sent: Saturday, March 22, 2003 11:57 AM Subject: Re: [CR]I never thought about TIRES
> One annoying thing about tires is that they are almost never as wide as
> marked. I just bought some tires for a commuting bike. I bought a couple
> of Paselas 32 x 700C and a couple of Continental Sport 1000 28 x 700C.
> Fully inflated on the rim, the Paselas actually measure between 27 and 28
> mm, while the Contis are between 24 and 25. The Japanese have mismarked
> tires in this manner for decades, but European tires used to be truer to
> size. The really annoying thing is the extent of exaggeration varies with
> manufacturer, model and nominal size, so there is almost no way to know what
> size you are actually buying.
> Jerry Moos
> Houston, TX
> ----- Original Message -----
> From: "Scott Goldsmith" <email@example.com>
> To: <firstname.lastname@example.org>
> Sent: Friday, March 21, 2003 1:37 PM
> Subject: Re: [CR]I never thought about TIRES
> > A
> > >I guess Continental Grand Prixs aren't very era. What is, that is
> > >commercially available and looks right on a late 60s bike built up with
> > >early 80s campy?
> > >
> > >Ann Phillips Atlanta GA
> > >its too pretty to go back to work
> > Rivendell/Panaracer Rolly Polys, black real rubber, tan sidewalls,
> > small low key label, very generic looking. Only available in 27mm
> > actual size. Panaracer Paselas, more sizes, available with wire bead.
> > Avocets used to be good, now they have grey side walls, old ones
> > at the LBS have tan sidewalls, range of sizes up to 32mm actual,
> > wizard tire for cobblestones and bad roads.
> > --------
> > Scott Goldsmith
> > Milford, Ohio
> > USA.
> > National Anvil Association
> > Dedicated to preserving the lore of the American Anvil