37's or 40's???
you gotta go with the 40s you'll regret the 37s. whenever in doubt always go with the bigger option. but in your case with the wider rim you have no option but the wider 40"er. tires are supposed to be slightly wider than the wheel and sorta have to squeeze in a bit at the bead. NOT be the other way around and look like a flippin doughnut.
My friend runs 40" m/t Toyo's on 22's on a 10" lifted diesel excursion and it looks good. He never offroads it. Uses it as a tow pig mostly. Anything smaller on that rim would not look good imo.




though

