People run 4 rears of the 20's without problems, I would assume the 19s would be fine too

Plenty of tire clearance with 10" width and +45 offset, with 285/45/19 tires all around as opposed to 10.5" width, +30 offset, and 315/35/20 tires all around

I say go for it!

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards