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Discussion Starter #1
I asked their opinion on using a 190/55 rear tire. Guess I should have expected this response: " Thank you for contacting Kawasaki Motors Corp., U.S.A. We are unable to recommend and/or confirm fitment of after market parts for our units. We can only recommend and/or confirm OEM parts. You would have to check with the manufacturer of the parts you are wanting to add to your unit."
 

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Of course they'll say that. LOL!

That's basically saying they can neither confirm nor deny a 190/55 will improve things on your bike.

Just put it on. You will like it. I don't think anybody has put one on and hated it.
 

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Bob, be serious. Did you expect some other answer? If you put one on a 2017-2019 bike, be aware that you are changing a part on the bike that the traction control system was calibrated around. That's common sense.

Is it enough to cause an issue? For the most part, no. Probably. I suppose you will find out if/when you activate the traction control system? That's the problem with bad ideas. Often times bad ideas work...at least for some time.
 

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I'll give you 10 points for asking the Question, but considering Kawasaki specifically state to use only the "standard tyres" (as in 120/70 F & 190/50 R) in multiple places in both the Owners Manual and the Service Manual, why did you think that Kawasaki USA would deviate from that advice ??

The USA is the most litigious country on the planet. You can probably get sued for farting in public and causing air-pollution.

If K-USA provided advice contrary to their parent company's existing/published advice, and your were unfortunate to have an accident, there would be a queue a mile long of lawyers wanting to represent you and sue K-USA.
 

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Discussion Starter #5 (Edited)
Was hoping to get maybe an opinion from their engineering department, considering it is such a popular mod, that makes a noticable improvment. But, the lawyers win again. Question is, then, why did Kawasaki not use the 190/55? What is their big benefit for the 190/50? Gotta be something that would make the bike safer, as to avoid any future litigation. I imagine their engineers did some serious calculations so as to support not using the 190/55? Maybe unacceptable stress on the frame in certain circumstances, or less effectiveness of the traction control. Who knows. Maybe they purchased a million 190/50s and needed to get rid of them.
If the 190/55 improves handling in a turn as people have experienced, why would Kawasaki not want an N1K that handles better?
 

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Discussion Starter #6 (Edited)
Assuming this is correct, looks like the 190/55 tire will raise the back of the bike almost .4 inches. Question is, does that mess up anything in the IMU/Traction Control operations? (you have to re-enter the numbers for the motorcycle tires) (and at 65 mph indicated, you're actually doing 67) https://www.discounttire.com/learn/tire-size-calculator?utm_source=bing&utm_medium=cpc&utm_campaign&utm_content&utm_term&ef_id=76d102e7ca8518e7f8125d1943b245ae:G:s&msclkid=76d102e7ca8518e7f8125d1943b245ae&utm_campaign=DT|B|NB-Tires|Highly_Competitive|BMM&utm_term=+what +size +tires&utm_content=DT|NB- Tire Calculator
 

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I am a fairly new member of this forum, but even I know from using the "Search Community" function that the question of why Kawasaki has stuck with a 190x50 rear tyre for over 10 years, and continues to stick with a 190x50 rear tyre on the 2020 & 2021 model has been discussed ad nauseam.

Kawasaki's engineers have obviously made a conscious decision which we can only guess at. My money (guess) is that they are staying within the design parameters of the TC unit.

The ZX-10R comes stock with a 190x55 rear tyre, so Kawasaki is not disenclined to use a tye of that size. However, the ZX-10R also uses completely different TC / IMU / ECU units.

So, we can only :--
  • (1) learn to live with the bike "as designed",
  • (2) fit a 190x55 rear tyre and hope the TC does not become confused in some critical situation
  • (3) fit a lowering link to raise the rear end but not confuse the TC
  • (4) buy a ZX-10R which comes with a 190x55 rear tyre as stock and which has stock suspension & handling that puts the N1K to shame.
 

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Bob, they do not want this: Honest to god, this is exactly what happens. The rider here didnt do anything wrong. If this happens, sometimes you can get out if it with ful throttle. I am 1 for 2 using this method. The 2 ended up with broken ribs and a punctured lung.

Kawasaki has to try and use 100% safe geometry. Think of the posts we have seen where riders are taking bikes up to top speed. Bikes that have 35,000 miles on them and have worn suspension parts.



Also think about stock suspension, overloading the bike, passengers , saddlebags, and tail trunks.


So, the 190/50 keeps the back end low. The rear shock is also set up to do this. The 190/50 tire costs less and it was never that big of deal, anyway.

If, and I say, "If" the tire is a problem, and its traction control related, the issue with be the tire shape. As you lean, the profile isnt going to match if it's set up for a 190/50. Figure it's a slightly larger diameter as compared to the 190/50.

Murph gave the options. The link , or a longer shock is the best option. Murph described it as a lowering link, but we would be using it as an adjustable link and setting it up to raise the bike.

Both options let you raise the back end more than the 190/55 could do and the bike needs that to handle properly, so why not give it a permanent fix?

This info doesnt relate to the 2020 bike. No one is 100% sure of what changed, but it sounds like something did, and it appears that this bike doesnt need this modification.
 

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  • (4) buy a ZX-10R which comes with a 190x55 rear tyre as stock and which has stock suspension & handling that puts the N1K to shame.
I'll go with 4.

I haven't had any issues with switching to 190/55, as far as any electronics lighting up. Anecdotal, too, but I put TC on when I practice 0 to 60 pulls. I go WOT and the front wheel doesn't lift.

Rcannon, I have seen you post in other threads too that using the 190/55 could in theory compromise the IMU input. My follow up questions are, would you recommend the 2017 and newer models to stick with the 190/50? Also, i did not see in Ivan's list of mods to the ECU anything about altering IMU inputs, but does a modded ECU affect that as well?
 

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That's like asking Volvo if they recommend driving without wearing your seat belt. Even if you knew an engineer who works for Kawasaki they would tow the company line if they want to keep their job.
 

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CudaBob, you're over analyzing this my friend. Don't worry and just do it, reap the benefits.

A good TC/ABS system should have some form of logic programmed into it to account for small variations in a tire's circumference. That can be caused by an under inflated tire, a heavy load in the rear that pushes the tire further and reduces its overall circumference, tire wear, tire manufacturer sizing variance, and just to give an owner the option to fit a slightly different tire if the factory specified tire is not available (say you're traveling far from home). A manufacturer who puts a rigid requirement on exact tire size and circumference is just setting themselves up with customer complaints. I don't know what that variation is that will cause en error in the TC/ABS, but clearly, based on many other people's experience, 190/55 tire size is not one of them. It's too small a variation of less than 5%.
 

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..If you include " many others" its only fair to mention those who had errors, too. There are many riders who have never activated the tc system, as well.

The tc system is a completely separate function within the ecu. Ivan does not, and will not alter that software. Ill ask him if I have permission to say more than that.

There is some variance in the tc system that will compensate for tire wear, but it doesnt calibrate itself around a different tire size. At best, its not throwing an error. That doesnt mean the same thing as ok. You wont know rhe ok part until you really activate the tc system , while you are leaned over.

If this were an awesome, incredible change and you had no choice, maybe it would be worth it.

Its not. Its about a 50% , temporary fix....the tire wears and you lose the height...and its about 1/2" too short to fix anything, even when new.
 

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Just for some more data....

Some are running 15/39 sprockets, which is a 4.87% change, this doesn't seem to cause the instruments to go haywire.

Changing to a 16/39 does cause the instruments to go haywire, sometimes intermittently. This is a 10.81% change.

A 190/55 with stock gearing is roughly a 2.96% change. (some have had issues)

A 200/55 with stock gearing is roughly a 4.6% change. (don't know of anyone running a 200/55 on the 17-19 N1K)

By these figures, the breaking point for the IMU to complain is somewhere above 4.87% of change.

Theoretically a 15/39 sprocket combo, 190/55 or 200/55 will likely work without causing the dash to light up. But like rcannon said, just because the dash isn't lighting up doesn't mean the IMU will behave as designed when needed, due to the different RPM/wheel speed than what the IMU is expecting.

Sadly, it's one of those things you won't really know until you need it, unless someone finds out more details about the inputs the IMU uses.
 
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Since tire sizes differ by brand, would be interesting to see exactly what a new stock rear 190/50 actually measures vs say an actually measured M9RR, Pirelli Angel GT, etc........ to see how much of a percentage change there is between the stock tires and other popular replacements that are also 190/50's.
 

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Sadly, it's one of those things you won't really know until you need it, unless someone finds out more details about the inputs the IMU uses.
Totally agree. If someone does find more detailed specifications from Bosch regarding how specifically these systems work, please let us know. I have searched several times, but haven't found anything beyond the usual marketing materials.

If I were a wagering man, I'd bet that Kawasaki implemented the system with a significant safety margin relative to the predicted failure limits of the system. This is why first-rate riders describe the TC and ABS interventions as sometimes "too conservative" or "premature" when riding hard. Let's say the Kawasaki-engineered margin of error is maybe 10 - 20%. And then they set the dashboard fault threshold at something well within that margin -- maybe 5% as your excellent list of known data points suggests.

Given all that speculation, I would further speculate that if your changes don't cause a dashboard error, then you are safely within the ICU's operational margin of error (as OCL implied). The 190/55 tire is almost certainly an example of a "within the margin of error" modification. But I also agree with RC that the safer, more considered way to adjust the geometry on these ICU-equipped bikes is via the shock or linkage.

I really wish I knew more about how these systems work. The older ABS systems were cool in their own way, but the operational parameters were pretty easy to comprehend. There were only really two inputs:

1) has this wheel's brake been activated?
2) is the wheel in question rotating?

If the brake was activated and the wheel wasn't rotating, then the tire was sliding and the brake intervention would begin modulating brake pressure.

These new ICU systems appear to be making predictions about when traction is likely to be lost. Because if the system were waiting for actual slippage, like the old ABS, then it wouldn't need to know tire circumference, would it? But, at the same time, it can't totally be prediction-oriented because it's impossible for the system to know, for instance, whether or not the road is wet. So it must be using measured slippage somehow to set the real-time traction threshold.

Like I said, I really wish I knew more.
 

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As many people in this discussion, and multiple discussion elsewhere on the forum, have said "we just don't know".

We do know that some people swap over to a 190x55 and have no problems, while other people do have problems, so it really is a "roll the dice" situation.

As for me, I don't know why the Kawasaki engineers have stuck with a 190x50 tyre, but they have done so for over 10 years, an continue to do so even on the 2020+ models.

I trust their judgement. It might be "conservative", but that is OK with me because while I "don't know" the Kawasaki engineers "do know" !

This is why I decided to use a "Lowering Link in Reverse" to raise the rear end of the bike and achieve a similar result as the 2020+ models, but without straying from what the Kawasaki engineers wanted.

Oh, for what it is worth, I just fitted an new Pirelli Angel GT2 190x50 rear tyre to my N1K yesterday. :)
 

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This isnt exactly information about this specific bike, but it's the best I've seen, anywhere, about how this system works. It also explains why Ivan spent several years developing a flash for this, and why someone else might have had one in a few weeks.




 

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Do we all agree on what we are trying to solve? For me, I always felt a hitch, or a reluctance to turn. Once you forced it past this spot, no problem, but it was this feeling like you wanted to turn, and the bike said, "No". Is this what you guys were trying to accomplish?

Earlier I called the 190/55 a partial solution, or something like that. Heres where that thought comes from.

When you buy a rear shock from Traxxion Dynamics, the shock is built like this. Let's say this is for a 200lb rider.

Stock shock length is 350mm. The spring is also more stiff. When it's all said and done, the bike handles very well.

Overall, With preload properly set, the tail light ends up about 1 inch higher than it was in stock form.

The 190/55 tire gives you @ +5mm. If you figure that part in, now what? The larger tire could cause a tc issue, and never solved the problem in the first place. It would still be @20mm too low.

This would be closer to the full solution. Also, its adjustable. Once its mounted, you can tune it with a crescent wrench.

59.99.

2011-2017 Kawasaki Ninja 1000 Black Adjustable Lowering Link | eBay
 

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Pretty much everyone agrees the stock tire isn't great, but what about a 190/50 from a good brand? Has anyone rode, say a Dunlop Q3+ or Pirelli AGT at 190/50? Did it still have the maneuverability issue?
 
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