725D issue with wheel

[Scrubcadet10]

That's either part of the bearing, or it looks like a snap ring or retaining ring of some sort.

 

[Hammermechanicman]

At the very least you will need 2 DP bearing assembly part #120048. Grasshoppers use an odd bearing. Clean all the grease off. Check the wheel hub and thru bolt for wear. Most likely it just needs new bearings. You need the center spacer and the thru bolt and nut. The rest is from the bearings.

 

[AVB]

They are part of the wheel bearings. See image below