Z3n
Squid.
^^ Sorry if I was unclear / incorrect. I understand and agree with what you say, the point about the aspect ratio was to indicate what is measured vertically to get the aspect ratio. I had understood that it was the sidewall that was measured, but if it's something else, OK. What is actually measured / designed for?
For the resulting shape of a tire on a narrower rim, what you say makes sense. I shouldn't have guessed about what shapes might result, but should have just noted that the shape does change and people should be aware of that. (And let whoever give the appropriate details.)
No problem. Communicating about these concepts can be really difficult over the internet, which is why I was looking for feedback to get the point across more clearly
I believe you are correct in that the aspect ratio measures the height of the sidewall. I'll double check on a tire tonight. I hadn't even thought about that.
For the most part, the change in shape from running one size up or even 2 sizes up isn't noticible to your average rider. Some may even feel that a fatter tire is "more stable" as you've got more contact patch on the ground and that will slow the steering on the bike. There is a difference in profile, how extreme the effect is will vary depending on the tire, the bike, and the skill and riding style of the rider.