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Tire and rim standards move closer to conformity after industry push

Published March 6, 2019

Editor's note: A version of this article appeared in the Feb. 1 issue of Bicycle Retailer & Industry News. We've attached a letter to the industry on the subject by Challenge Tire's Morgan Nicol.

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GRAND JUNCTION, Colo. (BRAIN) — Installing and removing clinchers could become a bit easier in the near future as the industry has completed work with two standards bodies to revise dimensions for tire bead and rim diameters. Standards makers at ISO and ETRTO have worked together, for the first time, to revise and harmonize the ISO 5775 rim standard and the ETRTO tire standard.

The revision of ISO 5775 should be published this year. A spokesman for rim supplier DT Swiss said the company will design new rims according to the standard.

“We’re confident that this new version will clarify the situation,” said Taylor Bushong, DT Swiss’ marketing coordinator for the Americas.

Rim makers have had to develop designs and manufacturing standards without knowing the tolerances that all tire makers were using. From the other side, tire makers had to deal with a lack of standard dimensions for rim well depth or rim bed profile.

“Tire and wheel companies are definitely using these evolving standards to build future product because the new standard is so logical and functions so perfect compared to current chaos,” said Morgan Nicol, Challenge Tire’s technical director.

Many new tires and rims are already being made in compliance with revised ISO 5775, even before it has been officially published. And though the revision is substantial, there is no problem mixing older tires and rims with new production, industry experts told BRAIN.

“I think the new ISO/ETRTO standard will make things a little easier to mount, dismount and seat a tire across all wheel, tire make and model combinations,” said Jason Fowler, SRAM’s wheel category manager.

“Its primary concern is safety, but ease of use is also being considered, while still allowing room for design flexibility — where it doesn’t risk safety,” Fowler added.

ISO, the International Standards Organization, has been working to harmonize all regional standards, including those from the U.S. CPSC, ASTM, Europe’s CEN, Germany’s DIN and Japan’s JIN.        

ETRTO, the European Tyre and Rim Technical Organization, is the most common tire and rim standard in the industry. Though ETRTO covers rim and tire interfaces for all wheeled vehicles, bicycle tires have unique issues. Auto and truck tires are generally installed and replaced by professionals, but bike tires are often handled by consumers with varying tools and skills.

The revised ISO 5775 rim standard defines how deep rim wells should be, how high tire sidewalls extend above the rim bed and consequently standardize enough of a rim’s internal profile that tire fit is simplified and made safer.

“It is easier to build the rim. It is easier to build a tire to fit tight but still be mountable with your thumbs,” Nicol said.

“Tires and rims made to the new ISO 5775 are safe at defined operating pressures and can be removed normally without tools using the proper technique or at maximum with simple tire levers. This is a massive improvement compared to the past 10 years,” he added.

The new standards are expected to be published this spring.

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