I''m old so bear with me. Back in the day many tires, particularly British, would have two arrows marked in opposite
directions - one labelled front and the other designated as rear. The front or rear position on the bike determined
proper rotation direction. I customized a 1994 Fatty with 18 inch wheels and used the same tire front and rear
without any problems utilizing switched position / rotation.

 

It had to do with the Harley 402 and the equivalent tire 404? that was used on metrics. Been a few years but the metrics ran the tire (marked differently) in opposite direction from Harley.

 

I know your not trying to give me a hard time. Keep in mind especially in this area of the forum when I'm replying to someone, I'm not only replying to them, but an entire audience present and future. So I'm kind of trying to keep it relatively simple for everyone to gain at least a small understanding in the event they too decide to go DarkSiding and even going Double Dark. That plus I have to be extra sure of what I'm saying since it appears I am the only female rider on these forums who has gone to the dark side, even double dark with no guidance other than information I had gleaned over the years from various sources. Never mind I do my own wrenching as well as tire changes using hand tools no less.

I suppose first one needs to understand that motorcycle tires have specific jobs by their design. The rear tire is mainly for traction or driving force where the front tire is responsible for braking and steering. And by design and engineering each has rain sipes to perform the job of removing rain from beneath the tires for optimal traction as well as braking.


With your questioning the rain sipes, I decided to do more research because in theory anyway, the rain sipes should be going the same direction as the rear tire. The same way directional tires are mounted on a car both front and rear. I mean, aren't rear wheel drives similar to a motorcycle since the rear is responsible for traction and the front for braking and steering? Yet both sets of front and rear tires are mounted in the same direction. Aside from the lean angles, what is the difference? BTW, of the dozens of sites I visited earlier looking for answers, I wasn't able to find a single one that had a viable answer. With the science, engineering, and design behind it, one would think there would be tons of information out there but most are theories at best.

There are some who have ventured to mounting the rear tire in the designated rotation and have said they had no issues running them that way. Heck, here are two pictures of different bikes. One with the rear tire mounted the same as the original front tire, and one mounted the same as the rear tire. I'm not quite sure where I snagged those pictures since I've had them for a while. Heck, it may have even been from here. (They're running 180 rear tires probably on aftermarket rims with modified or aftermarket fenders)


So now I'm thinking, do I throw science, design, and engineering out the window and make another path on my own? I'll have that answer in a day or 3. I need to run some calculations and simulations before I decide.

 

LOL exactly! I have seen front mounted rears going both ways as per your pics.

I have heard folks say that the rear belts are designed for acceleration first and braking second. Whereas front tires are designed for braking and handling first. These folks say they put it on backwards because otherwise it might damage the belt due to hard breaking if they did not. I have never agreed with that theory.

I have also heard a few folks say that Battle Ax rears run on the front get splits in them unless mounted backwards. They showed pics of damaged tires. Still that does not make sense to me and mine never got splits.

When I ran double dark on the old bike I mounted the tire frontwards because I figured it would pump out water better that direction. Am I right? Who knows? I can tell you that bike ran through heavy rain at highway speeds like it was on rails. The other good thing that might or might not have anything to do with direction was the bike had stupid good emergency braking. (don't ask me how I know!)

Does any of this prove anything? Not really... It's just my thoughts on the subject.