Falken Azenis Rt-615 Question

Okay, so I got some 16x7 rota grids for christmas. My heart is set with getting the azenis, but the thing is, I've heard the typical tire for 16x7's are 205-45-16. Falken doesn't make azenis in 45's. The only two sizes are 215-45, or 205-40. The 215's would be too wide, and the tires would stick out a bit. But, my friend has some rota gt3's with the 40 series tire. He said they were alright, and have caused him no trouble. From what i've been told, the 40 would be too small, and it would cause me to be in higher RPMs while im cruising. So what do you guys think? Would the 40 series be okay?