This is a really stupid question so please bear with me. What do the three numbers mean when referring to tire size? Ex. 275/65/20 or 275/55/20. I'm guessing the last number is the rim size so what exactly do the other two numbers mean?

 

Check out this post I put out a while back, should help explain:
https://www.f150online.com/forums/wh...tire-size.html