Tire mystery.

We'll have to look for other markings. I haven't yet found a 100/90-18 rear on Kenda's site that Texas linked to.

I suppose it is possible that Kenda quit making that size in a rear tire since your buddy bought that one.

Yes. I wonder if I have an old Dennis Kirk catalog laying around.

I had a friend with the opposite situation. He bought a bike and when he went to change the tires there was a front tire (from a Harley Davidson) on the back!

How does the tread pattern differ front to rear when they roll the same direction?

I met a guy riding a new Victory once that said my front Avon Roadrider was on backwards and I told him about it being a dual purpose tire for the front or back but he insisted that the tread was wrong until I looked at his front tire and it had the same pattern as mine, he was bummed
Going on probably my 5th set and like the way they track, I try not to ride in the rain but I have never noticed anything squirrely about them.

Both tires in same rotation direction. I think the one in the original post is a blem.

Avon Roadrunners 18/4.00 rear and 19/3.25 front ( universal )

It's still a mystery, I'm afraid. We have an email into Kenda, but no reply so far.

The main thing to figure out, is how to determine if a tire is a front or rear based on looking at the actual tire. We haven't found any obvious "front" or "rear" mark. We have a few other bikes with Kenda Challengers, and on those, the rear tire is marked "drive" instead of "rotation".

Both tires in the original post are marked "rotation".

Both tires in the online graphic are marked "rotation" but those might not be photos of an actual front and rear tire pair.

Kidkawie wrote: How does the tread pattern differ front to rear when they roll the same direction?

Even though they roll in the same direction the major forces that act on them differ. The major force on rear tire is applied when accelerating - this force is pushing the bike forward so the tire is normally oriented so it can provide it best traction in that forward direction. The major force on the front tire is applied when the brakes are applied - this braking force is in the opposite direction compared to that of the rear tire during acceleration, so the front tire is normally oriented so it can provide the best traction when braking. Ed

In addition to what Ed said about the traction, it's possible the inner belting construction is designed so that it is optimized to take rotational load for one direction or the other.

Since the same, seemingly directional pattern can be used either way for some tires designed for front or rear use, I guess the water traction is not a factor. If you've ever done much riding in the rain, though, you know traction is a BIG deal in the rain , so it's difficult for me to be comfortable thinking the pattern direction doesn't matter.

As BlueJay shows, he's got two tires with the same tread pattern, but one can be used in either direction, and the other can only be used in one direction. That seems to imply there is something internal, other than just the tread pattern, that determines direction. In his case the one-direction tire is presumably constructed differently than the two-direction tire.

Well, I am certainly befuddled. This conversation has shaken loose a very dim memory from when I rode a 750 twin. I had a Metzeler ME 33 on the front, and I seem to remember thinking that the tread pattern was backwards, making me think the grooves would channel the water toward the center of the tire instead of away. Even so, I road in a couple of torrential downpours, once the water was just over the foot pegs, but never any sign of loosing traction. Must be magic.