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Discussion Starter · #1 ·
I got it cleared today that it would not harm to my bike to move my tire size up to a 150 I checked out a video on youtube where it shows a new 250 Ninja with a 150 on it and it looks sick!! Do you guys think this would hurt my engine?
 

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The engine will be fine. My question is, does it effect the speedometer? and/or tachometer? That's what I'd be concerned about...
 

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the speedometer is run off the front wheel...so you'll be fine there. it won't throw off the tach either because the engine will turn at the same speed regardless of the size of the tire...or if there even is a tire on at the time. for example if you rev the engine in neutral the tach moves even though the tire doesn't.
 
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limegreenlighting said:
It shouldnt mess the speedo up cause the 150 tire is also a 17" tire well that is atleast what I think?
:)The speedometer cable is hooked up the the front wheel. :)
Speedy
 

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Here's a post I put up on another thread to explain tire size and the effect on speed of rotation in relation to the front and rear wheel. You can use the formula I've put in to calculate the circumference of whatever tire combination you like. Hope it helps.

http://www.kawasaki.com/Products/detail.aspx?id=359&content=specifications

Checked the kawi site for tire size specs...so here's the info.

Front tire 110/70 17
Rear tire 130/70 17

The first number (110 and 130 respectively) designates the width of the tires.

The second number (70 on both) is the aspect ratio of the tires. This as a measure of the sidewall height measured as a percentage of the tire width.

70% of 110 = 77mm
70% of 130 = 91mm

The last number is the rim diameter- 17" both front and rear.

With this information you can calculate the circumference: C = pi*D
1 inch = 2.54 cm = 25.4mm..... 17 inches = 431.8mm

Front tire C = 431.8 + (77*2) (front tire aspect ratio)* pi = 1839.41mm
Rear tire C = 431.8 + (91*2) (rear tire aspect ratio)* pi = 1927.33mm

....so when the front tire has made 1 revolution, the rear tire still has about 87.9mm to go before it makes 1 revolution. So the front tire does indeed rotate faster than the rear tire. Sorry about the long post, I do have a life ha...just bored and wanted to verify this answer for myself.
 

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Steezy McBreeezy said:
yeh you'll be fine.

quick question though.. why are u going with 70 profile instead of the 60?
for example using that equation...

130/70 17 (factory rear tire)
C= 431.8 + (91*2) * pi = 1927.33mm

150/60 17
C= 431.8 + (90*2) * pi = 1921.05mm

150/70 17
C= 431.8 + (105*2) * pi = 2015.25mm

...as you can see the 150/60 17 is much closer in circumference to the factory tire than the 150/70 17.
 

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the 70 gives u a thicker tire than the 60 profile by 15mm.

personally i like the thinner tire and thats why i went with a 150/60 instead of a 140/70 cuz thats thicker by 8mm. Its less of a ballooning type look.

some guys who tracked there 250 went with a 60 profile instead of a70
 

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limegreenlighting said:
Whats the difference between 60 and 70? The factory 130 is a 70 so why shouldnt the 150 be?
that second number is the aspect ratio. that number represents the height of the sidewall of the tire as a percentage of the width of the tire. eg: 70% of 130mm is 91mm...so the sidewall of the tire is 91mm tall. conversely, 70% of 150mm is 105mm....so that tire's sidewall measures 105mm. that's about 14mm more height in the sidewall of the tire, but it actually results in a tire that is 28mm taller because that height is added at the top and bottom of the tire. by going with the 150/60 you keep roughly the same tire size in comparison to the height and circumference but gain about 20mm in width. a tire with more circumference will rotate a little slower than stock and will require a little more power to rotate, although the extra power needed will be pretty much negligible. hope that makes sense. btw, having a different tire circumference would throw off your speedometer if it was measured at the rear wheel.
 

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Discussion Starter · #15 ·
But I want the bubble look. Thats my reason of going to a bigger tire and I will be able to take curves a whole lot better.
 

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Great info I will just wait until the tire wears out ...too bad they don't come out of the dealers with a wide tire... the new ninja 250 can fool almost anyone except with the rear tire... they don't believe its a 250 engine. Lol
 

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to be honest, I'd go with the 150/60 17 if I were you. you'll still have the extra width that you desire while keeping the other dimensions of the tire relatively the same. plus you should keep in mind that with a greater aspect ratio also comes some extra sidewall flex. just my two cents though.
 

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Discussion Starter · #18 ·
Well I got the 150/70/17 mounted Saturday and it works great! A little stiff and harding feeling guess thats where its a new tire? Tho I guess Im gonna have to move my front tire up to a 120/70/17 to even things out?
 

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its not necessary to change the front to a 120.. it would be better to change the compound.

and i know u said u wanted to change to a 150/70 to take turns better but increasing the tire size wont help in that department that much. Im not trying to bash or anything cuz i went to a 150/60. Just be careful cuz the thicker profile on a smaller rim increases the chance of sidewall flex like what dknoll said

anyway, what kind of tire did u end up going with?
 
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I'm not expert in this, but. By switching to a larger tire aren't you adding unsprung weight/mass and changing the dynamics of the rebound damping in the rear wheel? I can see that the tire footprint is larger, but only when it's firmly touching the pavement. I'm curious about this. Would you let us know what sort of satisfaction the new tire gives?
Sleepy
 
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