I am replacing garage door and I am confused about r-ratings for insulation those garage doors come with. Have seen from r-6.58 to r-18. Have seen several with the r-6.58 rating and am wondering if the ones with the higher rating is overkill.

I live in Ohio and there is living space above and next to the one car garage, so I’m concerned with having it insulated as well as possible, because I don’t want to pay a lot for energy and heating. I don’t want to heat the winter.