"rim diameter" refers to the size of the circular outer edge of a wheel. It tells you how big the wheel is across, from one side to the other. Full definition
But I was asking about different aspect ratios, for a given total diameter, therefore variable rim diameter. (mechanics.stackexchange.com)
Why do the track guys run wide tires and wheels on the same rim diameter then? (mechanics.stackexchange.com)
The model - specific steering wheel stands out with its smaller rim diameter and a design which borrows from the double - spoke construction of the M light - alloy wheels. (motor-prime.com)