Gearing an 8xl Maxx - Wrong Motor?

[Sorb3t]

Ok, So I've just ordered a TeknoNeu 1515/1Y/F motor. Depending on gearing, this should be just right for 4s from what I'm hearing? and depending on gearing, I can do 5s if I want to later? What I would like to know is what temps I should shoot for in my setup. I don't want to run a fan but I don't want to hurt my new Neu. Without a fan, geared for ~40-42 mph, what kind of temps should I expect. I have a temp gun to check it. Thanks.