My garage doors, at least one of which is probably 40 years old, seem to be in need of replacement. They're both creaky wood from the Year Two. Each is 7' high by 8' wide. I've looked at a number of replacements, all of which are steel filled with polyurethane. The brands are Richards-Wilcox and Raynor. The Richards-Wilcox model is Protege. The Raynor is Centura. The Protege is 1 3/8" thick, rated R12. The Raynor is 2" thick, rated R18. The fellow selling the Richards door says the thickness doesn't matter since the panel with the windows has a lower R rating. He also says that R12 is enough. He has offered a 1 5/8" door at an additional cost of $150 per door.
I know nothing about garage doors except how to open and close them. I have no information about the brands and have no basis for comparison. And, I don't know how meaningful the difference in thickness is. Since there is a potential outlay of $2200 to get this job done, I thought it would be helpful get answers to these questions before making a decision and would be grateful for all advice received.
Thank you in advance for your help.