There is no 'technical' reason why 285/30R19 won't work, but in my opinion, the 30's aspect ratio in back appear TOO low profile paired with the 40's up front. I was made to buy the 30's for the rear when Bridgestone was unable to produce Potenza 35's as indicated in their specs. The 30's in back and the 40's up front just look mismatched. The manner in which they fill out the wheel wells is noticeably dissimilar.

So in my opinion, either stick with 35rear/40front aspect ratios, or drop BOTH the front and back one notch to 30/35.