[M_Quick]

Not sure what is causing this on the inside of my rim, so I'm asking for help!
It's just on the left rear, at first I thought it was from rocks and mud rubbing in there, then I thought maybe grease from cv joint. But it's smooth to the touch so no grooves from rocks, and dose not feel like grease or rub off. And cv boot appears fine.

 

[MizuriDirt]

Check your caliper for your rear brakes and see if it is leaking brake fluid. The tire looks like it is wet.

 

[M_Quick]

Yea tire is wet and so is CV boot, but from washing the quad.

 

[MizuriDirt]

Gotcha. What it is then that something WAS in there and fell out. Scuff it up again and see if it becomes smooth again. If it does it beats the hell out of me.