Heads up! We'll be briefly closed for travel, 2/24–3/9. Orders during this time will be fulfilled on our return. We'll be online so please tell us what we need to know. Thanks for your support, patience, and passion!
Thanks to open source initiative dDDirect, we have a handy and practical way to accurately anticipate the inflated size of a tire on a given rim. Without this or an actual trial fit, the same size tire can vary over 10mm in diameter, mounted to different rims.
This is a critical industry challenge, largely ignored at the present but confusing the performance of highly engineered bikes and wheel systems. See our library for a complete explanation of the system and these issues.
The tool is a sturdy plastic scale, 5.25" long by 3.5" wide. A discussion of its use is here.