In looking at a lot of tires, this occurred to me and has been bothering me.
Tread on tires:
You can have unidirectional. Usually we don't see that except for instance high performance Goodyears for street cars.
A good example is those large tractor tires. If you mounted 2 rear tractor tires to the same face, you'd end up with the sides having opposite tread which of course you would not do.
So the outside face of the 2 tires has to be different. When you do that, it essentially reverses the direction of rotation, is a way of thinking about it, and the tires being symmetrical, it looks, and is, exactly right.
Same drill for street tires. They have to be symmetrical to be unidirectional or it would look strange.
If you have OWL on only one side of the tire, then, you cannot mount different faces. Just a side note. I mean, you could, but you'd lose the lettering if it was only on one side of the tire.
So leaving aside unidirectional since it doesn't really apply to us (I don't think); it is just to get in the mindset of what happens when you mount the tire with one side or the other facing out.
Here's the thing that bothers me. If tires are not symmetrical tread (bisecting the tire, the 2 sides are mirror images), no matter how you mount them, they will NOT be symmetrical side to side. That's what gets me because although it's true the truck is not symmetrical in lots of way, the body and general shape of it at least outside is intended to look symmetrical.
I know it seems like, if you flip a tire over, that would reverse everything.... and it does (as in the tractor tire example).... but if it's not symmetrical, what you end up with is the tread on one side is not a mirror of the other side. Like, you have two lefts or two rights. There is no way the left and right tires will be mirrors.
So if there is any intent in the tread design to, for instance, channel water to the outside, it will channel to the inside on the other side of the truck.
Take for example this tire, which I'm looking at as a probable when I upgrade tires:
Mickey Thompson 52510 Mickey Thompson Baja Legend EXP Tires | Summit Racing
That is not a symmetrical tire. No matter how you turn it or flip it, you will have the lines that you see running diagonally through the middle part of the tread running the same direction. They won't be mirror images. As I said it's like you will have 2 lefts or 2 rights in a sense.
To me it seemed like flipping the face - for instance those M Thompson tires you could do that as they are not OWL and it looks like there is no front/back, I think the faces are identical - it seemed like flipping the face would do the trick but it just doesn't work that way. I made little mock up tires/tread and turned them around and turning something asymmetrical 180 degrees does in fact reverse it but if it's not symmetrical you end up with that weird situation that is bothering me. Obviously it's not terribly important or it things wouldn't be like that, but you see what I'm saying. To me the two sides should have the tread as a mirror of the other side. A lot of tires look on first glance like that's true, but, they aren't. Regular street tires probably just about always are symmetrical, but not a/t tires.