Just curious as to what brands use 1/2 or 5/8 width belts on there decks. My cubs with 54 inch decks use the 5/8 belt. My Brothers older RZT 50 uses the 5/8 belt also. It still has the original belt with over 850 hours.
All depends upon the load on the blade pulley
There is only so much torque a 1/2" belt can handle before it lets go
Mostly 5/8 belts got used on 2 belt systems where there is a single belt driving a double pulley directly from the engine then a 1/2" belt driving the actual blade pulleys
There is also a limit on how far you can bend a V belt backwards .
It is a lot more complicated than most would appreciate