We have similar set-up. Sometimes they squeal, sometimes not. Seems to be worse when the humidity is high. It tends to be quite dry here and the rims and pads get dusty. This seems to decrease squealing.
The other thing that I have found is that when rubber transfers from the pads to the rim, the pad rubber and rim rubber wants to stick to itself & sets up a shudder & then squeal. I have in the past cleaned the rubber off of the rim with a solvent and scotch-brite pad and/or wet-dry sandpaper.