My Dk45 has 17.5 x 24's and they are 47 1/8" tall. I made that measurement with the tractor parked on concrete, with pressure in the tires great enough that there is no visible "sag". I made sure there was a lug at the very top of the tire,(industrial lugged tires) and ran a level from the top of the tire, out to the side far enough that I could get an accurate measurement. Of course, I have no way of measuring the wear on my tires, but I don't think there is any measurable amount - I have 600 hrs, & my tractor is a "hay" tractor (I never pull heavy loads)
I agree with the fellas who say the rims are (probably) different; 2 1/2" wider tires are nothing to "sneeze at"! I measured my rims, but there is a certain amount of "eye balling" involved, so I would not 'guarantee' the measurement any closer than +/- 1/2". I measured from (basically) bead to bead, and came up with 15 1/2". That was NOT measured from the "flare" that 'bevels' out from the bead (that would probably add another 1" + to the overall width.
I think you are wise to get as much info as possible; but in the end, the decision is yours. If I can help with any other measurements, let me know.
Good Luck