Tire Heights from those listed in this post:
255x60x15 = 25.04" tall
245x60x15 = 26.57"
255x60x15 = 27.05"
275x40x18 = 26.66"
265x50x15 = 25.43"

Doing the theoretical tire height math, the 255x60x15" tire is the tallest tire. I thought the 275x40x18 would be? The 255x50x15" tire is 2" shorter than the 255x60x15 tire. Looks like the tire profile makes a big difference.