BT45 standard rotation or reversed

W0QNX

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Here is a picture to help. The white lines I've added are our tread layer splice and arrow for direction. This dragster as shown under power is fine as mounted because the splice is being dragged across the pavement under power across the splice. Now at 100 mph lock up that rear tire and you can see the splice joint will be dragging the wrong way across the pavement trying to tear apart the splice.

Leave the tire the same arrow direction and move it to the front. Still wrong way under hard braking. But since the front is not powered we can fix the problem by reversing the tire.
 

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W0QNX

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To counter that argument, I would claim that the braking forces have to be opposite the direction of the wheel rotation, otherwise they'd make the wheel turn faster, not slower. And a skid is different from normal braking forces. If you crash, anything dragging along the ground is skidding, and the force is opposite the direction of travel, but its not due to braking.
Sorry but I can't agree. The same brake force applied while rolling is the same at the tread (mass pushing forward) you just applied more brake and locked up the tire. Hence a black line left while the rotating tire is sliding some under hard braking.
 
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Sorry but I can't agree. The same brake force applied while rolling is the same at the tread (mass pushing forward) you just applied more brake and locked up the tire. Hence a black line left while the rotating tire is sliding some under hard braking.
In between posts I finally resolved the force balance in my head. The brake pads are applying force in the direction opposite the wheel rotation, and the pavement is applying force in the direction of the wheel rotation. If those forces are balanced, you have maximum braking power. When the brake pad force exceeds the pavement force, the wheel locks up. Makes perfect sense now, just had to think about it a bit too long to figure it out.
 

T_C

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I hit water more frequently then I hit max brake power. So I'll stick with keeping the tread in the direction it was designed for optimal traction rather then trade it off for a slightly possible scenario of lamination separation.
 
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Paawpabear

Paawpabear

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Guys, this has turned out to be an enjoyable and very informational thread. Thank you for all who added their 2? worth and I for one have learned a lot.

Sent from my XT1254 using Tapatalk
 
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Another quirk to tire mounting showed up on a set of Pirelli snows we bought for the wife's Forester. They were marked such that only one side of the tire should face the outside. The inner half of the tread is substantially different than the outer side.
That tire has an inside circumference that is slightly smaller than the outside circumference. I forget what they call is but it causes the car to track better and has better control on high speed turns. Racers that run on oval tracks run one side of the car with the outside in. If you ever take the tire off the car, and roll it down the driveway it makes left or right turns, it will not roll straight.
 
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Here is a picture to help. The white lines I've added are our tread layer splice and arrow for direction. This dragster as shown under power is fine as mounted because the splice is being dragged across the pavement under power across the splice. Now at 100 mph lock up that rear tire and you can see the splice joint will be dragging the wrong way across the pavement trying to tear apart the splice.

Leave the tire the same arrow direction and move it to the front. Still wrong way under hard braking. But since the front is not powered we can fix the problem by reversing the tire.
Some tire used to be marked one direction if installed on the front and reversed if installed on the rear. Mostly smaller non specialized tires but I have seen that marking.
 

Earl43P

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I hit water more frequently then I hit max brake power. So I'll stick with keeping the tread in the direction it was designed for optimal traction rather then trade it off for a slightly possible scenario of lamination separation.
Here's the thing, if you compare a rear tire tread to a front tire tread you can see that the siping is exactly opposite.

As a double-darkside novice (about 70,000 miles ago, on two bikes), I compared the rear tire's tread (in this case a Pilot Activ) with a front E3 tire.
Since I ride in a LOT of rain, I wanted the siping to channel water just like the engineers envisioned. In the photograph, I matched the siping direction which means the rear Activ got mounted reversed from the arrow.

I care not a whit about belt plies, tread splice, braking force, etc. I would like to see the BT45 pictured just like below for siping comparison. For what it's worth, my 93 GL1500 delivered 36,000 miles on its first darkside front tire. It would have passed state inspection tread-wise, but I replaced it as a maintenance convenience rather than take it off the road for maintenance again later on.

Disclaimer: I don't own an ST (yet) but I have lots of miles darkside and double darkside on my Valkyrie IS and all double darkside on the 93 GW, currently >49,000 miles on that bike alone. I never did ride the 93 on standard MC tires, other than a quick neighborhood test ride when I bought it.



My only hydroplaning incident was on the 93 when its first rear Austone Taxi tire was just getting close to the wear bars in the middle tread. The front held steady as a rock, but I could feel the rear wandering off track at right about 50 mph in a gully-washer downpour. The water was pretty deep on the interstate when that happened, twice on the same stretch of road. Twice because I just HAD to recreate it after the first incident- which got my attention, big eyes - with an immediate steady throttle roll off as I covered the rear brake pedal, but never pushed it.
 

W0QNX

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I've ran the Activ backwards for the first 20,000 then reversed because of the "cupping". Two tires now and the only only hydroplaning I've had is the big fat rear tire darkside will usually slip before the front in rain.

YMMV but either way will work for me.
 
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So any decision on this yet? I've got a BT45 rear coming soon. Almost all front tires have the tread running to a "V" from the edges that points up to the front fender. I know about the rubber lamination direction but don't want that as my only factor.

Any front tires that have the tread running opposite? The BT45 kind of runs both directions.
 
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Got her mounted with arrow running backwards. Looks good with thick tread and wide profile. Raised the fork tubes 1/2 inch in the tree to keep same geometry. If running downhill slowly with engine off there is a slight vibration, can barely feel it with the engine on. As soon as you lean off center it's gone so must be the center tread.

front 130/70-18 B'stone BT45 Rear tire
Rear 205/50-17 BF Goodrich G-force comp-2 tire.
 

paulcb

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I've run a several rear BT45s on the front of my ST1100(s), reversed and not reversed. Like others, I can't tell the difference in wear or handling.
 
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Go look at the groove direction of a regular front motorcycle tire. now set a rear tire next to in reverse. notice anything.. Ahhhhhhh yep the groove direction is the same... That's why I run my rear tire reversed on the front...
 
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