Originally Posted by
Bob Dopolina
There are VERY specific standards for rims set down in ETRTO. The problem is many manufacturers have chosen to play fast and loose with the tolerances for a variety of reasons.
There are no set standards for tires. Tires are usually designed to the expected rim dimensions in ETRTO but since several rim makers are outside of ETRTO you start to see the differences.
Thanks Bob. Excellent and really informative information as usual!