The rim size makes a big difference. A 285/70/16 is different than a 285/70/17. you should go to a site like tire rack or something and compare tire sizes to get familiar with how they size them. If you go to a site that will convert a tire size to inches it's easier to understand.
265/70/17, you know that means they are 17 inch right? Do you have the new body style or old?
What year is your truck and what size rims do you have?
Thanks for the comment. They are 275/70/18 Goodyear Wrangler Duratracs. Any ?'s feel free to ask. Good luck with your truck.