Swapped out tires/rims on the 520. Don’t know why but the original deep offset rims were not on this unit. The previous owner had spacers between the rims and hubs. I replaced the Sears 23x10.50-12 tires/rims with a set of 24x12-12 tires/rims. Also Sears, don’t recall how I got them.
Since these rims were not offset enough I installed a 1” spacer on each hub. The tires just barely cleared the mower deck enough to install without removing the deck first.
picture #4 is with one of each size.
If I push snow with this tractor tis winterI may have to swap back in order to install a set of chains.