[bsmith0404]

Originally Posted by bobbecky

I have read this discussion many times, saying one size is an inch larger than the other, but when I research the tires, at least with the tires made by Goodyear, they are the same diameter, 30.7 inches.

The Marathon: http://www.tirerack.com/tires/tires....omCompare1=yes

The G614: http://www.trailertiresandwheels.com...l-trailer-tire

There are several tire size comparison calculators available on the web, the one I use shows the 85 is .9" taller than the 80. It's basically impossible for them to be the same size based on how tires are sized. The 235 is the width of the tread in mm, so both are the same, the 80 and 85 is the height of the sidewall based on a percentage of the width, so the sidewall on the 80 is 80% of the width, the 85 is 85% of the width. Obviously 85% is more than 80%. Since a 235 is 9.25", 80% is 7.4", 85% is 7.86" so .46" taller sidewall times 2 sidewalls (top and bottom) gives a .92" taller tire.