I would suggest asking this question in the wheel/tire forum so that the tire rack guys can chime in as they will give you the right answer.
My personal guess: I'm not sure sure about the direct answer to your question, but the 50 profile ratio on this tire has a lower max psi than the 45 profile (44 vs 50 psi), so I would probably lean toward keeping the cold temp for the rear no higher than the 35-38 range.
Best of luck!
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