Car Tires, where to put the better treaded ones?

Hi /r/Frugal

I know this question is a bit weird. My car is almost 14 years old. Since my usage is minimal I dont plan to do heavy investing on it. I have done tire rotation yearly or so. I drive carefully, in snow and otherwise and do not do rash driving.

My tires are worn, but the front ones have better tread on them than the back ones. Which is the safer way? To keep the better traction/tread ones in the front or the back? Are there risks for keeping them as it is?

Thanks for reading