What size tire (in inch measurement) would I need for an 80/80R16 tire?
No bicycle I know of uses that standard of measurement. Do you want a 700 x 23C or a 26 x 2.5?
the tire you're describing is as such: 80 is the section width in millimeters, 80 is the ratio of sidewall hight to section width (.80*80MM) and 16 is the rim size in inches. This is a VERY narrow, small tire for an automobile, or a motorcycle tire. This is not a bicycle tire. A common bicycle tire size would be something like 2.25 * 26 for a mountain bike or 700*23C for a road/racing bike.
So doing a little homework, you are looking for scooter tire? 80/80 would be about 3 and1/8 inches wide by 2 and 1/2 inches, top of bead to top of tread. 16 is the rim size 16 tall and the R stands for radial. Please do not mix radial and bias ply tires on your scooter, it will not handle well
