Re: [CR] Tire sizing - then & now

(Example: Production Builders:Tonard)

Date: Tue, 1 Dec 2009 19:24:18 -0800
From: Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>
To: David Boston <zzboston@yahoo.com>, <classicrendezvous@bikelist.org>, Andrew R Stewart <onetenth@earthlink.net>
In-Reply-To: <42125B5711004765BBFA0A67EBB551A4@ARSPC>
Subject: Re: [CR] Tire sizing - then & now


Sometimes the labels aren't even consistent. More recently, since ISO has become widely accepted, tires have been marked with the traditional size but also with the ISO designation. This has led to conflicting markings, especially on 27" tires. For instance, one sees tires marked 27 x 1 1/4, which would be 31.75 mm wide or 32 mm to the nearest whole mm, but the ISO marking will be something like 630-30 which will be closer to what it actually measures. Evidently these companies have a policy of adhering to ISO standards, but the traditional size marking are still fair game for creative marketing.

Regards,

Jerry Moos
Big Spring, Texas, USA


--- On Tue, 12/1/09, Andrew R Stewart wrote:


> From: Andrew R Stewart <onetenth@earthlink.net>

\r?\n> Subject: Re: [CR] Tire sizing - then & now

\r?\n> To: "David Boston" <zzboston@yahoo.com>, classicrendezvous@bikelist.org

\r?\n> Date: Tuesday, December 1, 2009, 7:48 PM

\r?\n> David- I tell my customers that it's

\r?\n> a size label, not a measurement.

\r?\n>

\r?\n> ----- Original Message ----- From: "David Boston" <zzboston@yahoo.com>

\r?\n> To: <classicrendezvous@bikelist.org>

\r?\n> Sent: Tuesday, December 01, 2009 6:14 PM

\r?\n> Subject: [CR] Tire sizing - then & now

\r?\n>

\r?\n>

\r?\n> List-

\r?\n> I was rooting through old stuff and found some Specialized

\r?\n> Turbo Infinity/SK4

\r?\n> tires marked 700x25. I was going to toss them, but decided

\r?\n> to do a trial mounting

\r?\n> and see how they would do. Great, as it turns out, but I

\r?\n> noticed the actual size of

\r?\n> these 700x25 tires to be smaller than the current day

\r?\n> 700x23 tires I removed, which

\r?\n> were Conti Grand Prix 3000s. Both measurements, across and

\r?\n> off the rim, were

\r?\n> smaller. Why is this? Have the numbers come to represent

\r?\n> something different?

\r?\n> They could be mis-sized, but I recall back in the day

\r?\n> during the introduction of

\r?\n> skinnier clincher tires that 25c would be the narrowest I

\r?\n> would want to ride on the

\r?\n> road, and today I'm riding 23c tires with no consideration.

\r?\n> Well, I guess because

\r?\n> they're bigger. So, have tires come to reflect the overall

\r?\n> cultural obesity situation

\r?\n> or is there some other "inflationary" cause for this?

\r?\n> Anyone else notice this in older

\r?\n> tires? Was this a gradual change or did I miss a tire

\r?\n> sizing revolution somewhere?

\r?\n>

\r?\n> Dave Boston

\r?\n> Tucson AZ USA

\r?\n>

\r?\n>

\r?\n>

\r?\n> Andrew R Stewart

\r?\n> Rochester, NY