Both these tires are 26x11.50 M/T ET Streets. The one on the left is on a 15x10 wheel, and the one on the right is on a 16x8. Note that the right-side tire is an inch taller than the other--that’s because you can’t trust the sidewall designation to know the true height of the tire. We’ve yet to see a tire manufacturer print specs that are the true size of the tire. Secondly, while both these 11.50s have the same measured tread width, the tire on the 10-inch rim has a much greater section width. The wider the rim, the wider the tire will be when mounted.