I'm not sure of the size but if you look under the hood mine tells me the part number. Take it to any parts store and they can cross reference one for you that will fit.
1/2x33 inch belt, manual calls for a 1/2 x32.60
94.5 in v belt.
1/2" x 41"
Gates
1/2 an inch
Deck belt is 1/2" wide 79" long. Tractor Supply has them pretty much every store.
70 inch
I just relaced the same belt on the same model number tractor yesterday and it was an 88"x1/2".
The 66 inch deck belt fits Murray 42 inch and 46 inch models 425303X92A, 425303X92B, 465305X92A, 465305X92B. The width is 11/16 inches. This belt size replaces Murray part numbers 37X112, 37X112MA.
84 inch
1 inch = 2.54 centimeters
The John Deere LX172 38 inch blade deck uses a 65 by 1/2 inch V belt. If you ask for a 65 inch belt at an auto parts or hardware store, there is no need for a multi-numeral part number.