My bike is early 2000s and came with Shimano wh-r540 wheelset and 26mm tires
googling shows ETRTO: 622 x 13C (internal width?) and 19mm (external width?)
I've successfully used 25mm tires but considering going to 28mm since I believe there is clearance everywhere important for a tire that wide
However I am questioning if the rim is too narrow to properly support a 28mm and that it will "balloon" defeating the benefits of 28mm
But I've noticed new bikes that come with 28mm typically have a very wide rim to support the tire so the tire sits more square or inwards and not ballon out
ie. modern rim + 28mm tire profile = /----\
ie. old 540 rim + 28mm tire profile = \----/
does it matter? will it defeat the benefits of 28mm for handling?