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(11-21-2015, 03:14 AM)CA200_imp Wrote: Wow, ok there are many reasons a street motorcycle tire is made
to go in one direction. Tread of course but also the way in which it is built. There are some very good you tubes on how a tire is made.
https://www.youtube.com/watch?v=outx807C7QI
The old way a tire is built on a drum and as the material is laid on
is over lapped somewhat so you want that joint to go facing back
so the power from the motor does not open that joint. I have never seen this happen on a tire mounted "backwards" but I have seen them
chunk apart as they get warn. Front tires are also made in this manner. If you think about it a front radial tire "cups" because you putting a big force on it in the opposite way that it was built. When you brake hard.
Tread design for fronts is whole different subject.
Rear tires of course have a lot more material on them. One thing I always remind people of is the contact patch on a street tire is no
bigger then a credit card. You are putting a lot weight and HP through
that small patch. Think of it as we are riding a balloon all the time.
Pirelli a few years ago came with a new way to build a tire. They built a machine controlled by a computer that put the material
on the drum in a small string and changed it as it went so no people
needed. They still make some of their sport tires this way.
I have some of my track day junkies switch their front Pirelli's around because they ware them out on one side more then the other. I always tell them it's wrong but you won't believe the tires I have seen from the track. Some of these people are real junkies and spend
all their time and money there.
I have tried to keep this simple. There is a lot of technical stuff on the net if you want to know more.
If you have ever seen them make a tire in person you won't feel bad about paying for them .
Keep in mind that tire flexes every rotation at it's contact patch. Now think about how many times it flexes in one spot on the tire after 5000 miles.
i've done track days and club racing. never heard of flipping a front tire. only rear.
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The newest race-spec Dunlop GPA's allow the rear tire to be mounted in either direction (bi-directional). Most tracks are much harder on one side of the tire than the other. A tire can get worn down very quickly, and while one would never usually do this for a race, privateers looking to get the maximum useful life from a tire will flip them the opposite direction and get another weekend of practice. It's mentioned as a benefit on Dunlop's racing tire website. These tires can be run as low as 21 psi for the rear, even lower depending on conditions.
http://dunlopracing.com/tires-products/gpapro/
