I believe they make 6”, 8”, 12” and 15” wide 15 inch diameter tires in the S/R line. If I’m not mistaken a 26-8.00R15LT tire is 26” overall diameter with an 8” section width - but the width is not always exact. Here is a spec sheet.
https://tiresize.com/tires/Mickey-Th...-SR-Radial.htm