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So, it's time for new tires, stock dunlops lasted ~3,200 miles. I am moving up to dunlop q3 tires, q2s were my favorites, and these are supposed to be better?!? We'll see. I was looking on here, and another member was asking about 190 tires (which I'm getting anyway, so I figured I'd write my results for the community. Now then, on with it right? Right.

I have had the stock 180/55zr17s obviously, and we all know how they feel. I will say my feelings for comparison anyway! Fizzer with the stockers had great turn-in, decent lean angle abilities, and fairly good grip both upright and leaned. However, I did feel that I reached the "slide point" early at higher speeds, and the feel left some to be desired (although this is more from the brand/model/sidewall stiffness than size, but I digress). So all in all a great setup, but will the other sizes be a great setup, or even a truly "EPIC" one? We will find out...

So, yesterday, I discussed my plan with a buddy who works at the shop I buy my shit from. I was going to do only 180/55 and 190/55 but he told me they had a tire that was "used" in 190/50 from a bike a kid bought and immediately put a 240/xx on (zx-10 i think?) anyway, these tires took the bike from the crate/truck it came on, to the showroom, and the to the shop...so maybe 200ft total. Brand new "used" tires fitted today after work, I can say the 190/50s suck azmar... Turn in was heavy, steering felt sluggish, that being said. It did have better stability at speed and on wheelies, it also seemed to rev up slightly faster, and shift earlier when accelerating hard. Overall, I'd say they felt like extremely squared off 180/55s. I will explain why for y'all that don't know too much about tire sizing...

The first three numbers denote width in millimeters, so 190/xx is 190mm wide, now this varies from manufacturer to manufacturer because they take this measurement in different places, but not a whole lot. The second pair is the tire height as a percentage ratio to width, so, 190/50 is 190mm wide multiplied by 50%(or .50 for you arts and literature folks) =95mm "tall." Now then a 180/55 is 99mm "tall". I say "tall" because that is inside "edge" of the tire to the point in the middle of the tread, so a 180/55 is overall 8mm taller. This means the circumference is 77.9 inches on the 180/55 and 76.91 on the 190/55, an INCH less per revolution of the tire!

Here is a cross section of the tires I am discussing courtesy sportrider.com

So we can see the difference here... Wide and flat versus tall and skinny (only discussing the 180/55 and 190/50). Im sure you can see why turn-in and steering would be affected negatively, as well as why stability would be better... If not PM me and I will explain in more detail, as I have more to cover here... Now then why would rev-up and shifting be affected...

The fz-09 is geared as follows

1) 40/15 or 2.66

2)38/19 or 2.00

3)34/21 or 1.62

4)29/21 or 1.38

5)25/21 or 1.19

6)28/27 or 1.04

With a final ratio of 16F 45R on the sprockets. (2.81 for y'all using that system). So, with the stock 180/55 tire you will be going these speeds at redline per gear, I will also include the rpm drop when shifting at redline(all theoretically)...

1)67.3mph/~2700rpm drop

2)89.7mph/~2300rpm drop

3)110.8mph/~1700rpm drop

4)129.9mph/~1600rpm drop

5)150.7mph/~1400rpm drop

6)173mph/top gear.

versus 190/50

1)66.4mph/~2900rpm drop

2)88.6mph/~2600rpm drop

3)109.4mph/~2100rpm drop

4)128.3mph/~1800rpm drop

5)148.8mph/~1600rpm drop

6)170.8mph/top gear

Obviously, above 130mph or whatever it doesn't pertain in a practical sense...

These may not seem like a huge difference, but it will alter the shift dynamics and the rev character of the bike. Also, torque multiplication comes into effect because of the difference in tire height. Basically trading speed per gear for torque per gear. Its a fairly complicated equation to get torque, so I'll only do 1st gear...

*(this part was an error in my work and is ammended on pg 3)Stock torque is ~60ft/lbs, so, 60*2.66(1st gear)=159.6ft/lbs, then 159.6*2.81(chain&sprocket gearing)=448.476ft/lbs. Now the tire is where it changes... the rear sprocket is 45 tooth, and is 9.75in in diameter, the 180/55 is 25.05in diameter, 190/50 is 25.03in diameter, so...

180/55=448.476*(9.75/25.05)=174.556ft/lbs

190/50=448.476*(9.75/25.03)=174.696ft/lbs

So, an extra .14ft/lb of torque at the wheel basically. This may sound rediculous I mean, thats not a huge difference. But remember,torque is angular moment of force, and it is accelerating at such a high rate in tire rpms compared to the engine, that horsepower(HP=(torque*rpm)/5252), or work being done, so in first gear, at the tire the HP is actually higher! For example, for the 180/55, at 35mph(2,217,600in per hour), the tire is turning at 28,467.26rpm, so... [(174.556*28,467.26)/5252=946.14HP] and 190/50=959.09HP, a 13HP increase more or less across the rev range. I hope y'all all can understand these mind-warping physics behind this. *

So, in conclusion, 180/55 is better for turning than 190/50, however, a 190/50 with give you "more HP" at the wheel in terms of torque being applied and work being done, meaning easier wheelies and better acceleration! If you have any questions or you feel i messed something up along this project of a write up, feel free to correct me or ask the question on the thread or PM me! Thanks for reading! I will have the 190/55 tire on the bike this weekend and will continue this, probably sunday.