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Discussion Starter #1
So, if you haven't seen me on the forums since I joined let me start with: I just bought a Suzuki Boulevard M50 last week. Looking at buy my wife a 2010 Honda Shadow Phantom in the next few days, probably this Saturday. The Phantom needs a new back tire but the actual size the OEM state is limited in tire selection. The size is 160/80-15 and I know on a bike I had in the past I was able to go a size bigger in the rear. So am I able to order a 170/80-15 on the Phantom, which would offer me more selections?
 

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Google the tire sizes you're considering. There are plenty of options for either size.

I'm running Michelin Commander II on my Vulcan. Available (I believe) in both sizes you asked about.

3G
 

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Discussion Starter #3
Google the tire sizes you're considering. There are plenty of options for either size.

I'm running Michelin Commander II on my Vulcan. Available (I believe) in both sizes you asked about.

3G
Just found a thread on a Honda forum about it . . . kind of. The end result was Phantom owners said you could move to a 170 without worrying about rubbing or modding.
 

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Going to a larger size will change your speedometer/odometer. If that's not a concern it sounds like you'd be in business.

It does look like the Commander 2 comes in that size and I think it's a great tire by the way.
 

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Discussion Starter #5
Going to a larger size will change your speedometer/odometer. If that's not a concern it sounds like you'd be in business.

It does look like the Commander 2 comes in that size and I think it's a great tire by the way.
But going from 160/80-15 to 170/80-15 should just change the width, which shouldn't mess with that stuff. Right?
 

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But going from 160/80-15 to 170/80-15 should just
The "80 change the width, which shouldn't mess with that stuff. Right?
"80" is the sidewall height as a percent of the width. Also called "aspect ratio." So the 170 will have about a 5/8" larger total tire diameter.

If your bike has a mechanical speedo drive that works off the front wheel your speedometer reading won't be effected.

If it works off the transmission or rear wheel, and you're better at math then I am, you could figure out what the approximate speed offset will be.
 

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Pegasus trapped in a human body on a motorcycle
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"80" is the sidewall height as a percent of the width. Also called "aspect ratio." So the 170 will have about a 5/8" larger total tire diameter.

If your bike has a mechanical speedo drive that works off the front wheel your speedometer reading won't be effected.

If it works off the transmission or rear wheel, and you're better at math then I am, you could figure out what the approximate speed offset will be.
I just checked, and it reads from the rear. Now, considering how speedos from the factory always seem to read high, going to a slightly larger tire would bring the indicated speed a little closer to actual speed.
 

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Discussion Starter #8
"80" is the sidewall height as a percent of the width. Also called "aspect ratio." So the 170 will have about a 5/8" larger total tire diameter.

If your bike has a mechanical speedo drive that works off the front wheel your speedometer reading won't be effected.

If it works off the transmission or rear wheel, and you're better at math then I am, you could figure out what the approximate speed offset will be.
I just checked, and it reads from the rear. Now, considering how speedos from the factory always seem to read high, going to a slightly larger tire would bring the indicated speed a little closer to actual speed.
Thanks for the info guys. There is a speed reader about half a mile from my house, so I could always ride by it a few times after to know my exact speed change.
 

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I just checked, and it reads from the rear. Now, considering how speedos from the factory always seem to read high, going to a slightly larger tire would bring the indicated speed a little closer to actual speed.
Good point Dash. It very well might get right on.

Thanks for the info guys. There is a speed reader about half a mile from my house, so I could always ride by it a few times after to know my exact speed change.
There's another thread somewhere that I mention a school zone radar reader and going one way my speedo reads low and going the other way it reads high so unless you ask a cop to give you a ticket you still might not know. But it should be close.:D
 

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Pegasus trapped in a human body on a motorcycle
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Thanks for the info guys. There is a speed reader about half a mile from my house, so I could always ride by it a few times after to know my exact speed change.
Good point Dash. It very well might get right on.


There's another thread somewhere that I mention a school zone radar reader and going one way my speedo reads low and going the other way it reads high so unless you ask a cop to give you a ticket you still might not know. But it should be close.:D
If you have one available, a decent GPS unit can be quite handy. As soon as I can get some sort of mounting figured out, I will be checking the accuracy of mine speedometer.
 

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Dash it is off 66 indicated is 60. It is off 1 mile per 10 like every other Yamaha
 

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Pegasus trapped in a human body on a motorcycle
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Dash it is off 66 indicated is 60. It is off 1 mile per 10 like every other Yamaha
My tires are a bit larger than stock. The speedo on my Max reads off the front tire, and I went from a 110/90-18 to a 120/90-18. The difference will not be much, but I am curious.

Ok... stock tire circumference is 81.04 inches. New circumference is 83.26. (these numbers are approximations, cause tires will measure differently between brands, and on different width rims)

Running the numbers, indicated 66 becomes indicated 64. A bit more in my case, probably, because the Avon Venom X tires seem a bit larger than numerous other brands of "equal" dimensions. (all I know is that my front fender seems to really hug the tire now)

I would guesstimate a 3mph difference at 60, in the case of the Phantom.
 
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