3.50-16=3.5 inch tire width x 16 diameter
3.60-16=3.5 inch tire width, with (3.6 - 3.5 = .10 or ten percent) a minus ten percent (leaving 90 percent) aspect ratio tire height to width. loosely giving you a 90/90-19.
this doesn't really get much more confusing, suffice to say that fractional sizes like 2.75 or 3.00, 3.50, etc. are 100 percent aspect ratios, or as tall as they are wide. when you get to the 3.60 or 5.10, or 4.60, these are the 90 per cent aspect ratio tires; the extra .10 that they added to the designation meant minus ten from one hundred (per cent).
