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Discussion Starter #1
I know there are many threads about rear tire size already out there. But none of them seem to have found the answers I'm looking for.

I heard of some people putting a 160 rear tire on the bike. I will be purchasing tires soon and I am thinking of putting a 150 on. Will it actually fit and seal properly? Or should I go talk to my tire guy about it?

Also.. This may be a dumb question, but, what benefits do I actually gain from having a large tire rather than a smaller tire? Will I get better grip around turns?
 

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Answers will vary, of course, but the way I see it, more rotating mass means more angular momentum, which will directly impact your ability to lean.

Let us know how it turns out.
 

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Discussion Starter #4
Answers will vary, of course, but the way I see it, more rotating mass means more angular momentum, which will directly impact your ability to lean.

Let us know how it turns out.
I thought about how it has more rotating mass. I really don't think it will be a big effect at all. Since it's already super light/easy to throw down.:)
 

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I know there are many threads about rear tire size already out there. But none of them seem to have found the answers I'm looking for.

I heard of some people putting a 160 rear tire on the bike. I will be purchasing tires soon and I am thinking of putting a 150 on. Will it actually fit and seal properly? Or should I go talk to my tire guy about it?

Also.. This may be a dumb question, but, what benefits do I actually gain from having a large tire rather than a smaller tire? Will I get better grip around turns?
Ultimately, this is a scientific answer, with objective-results. Opinions vary (informed or not)—but usually people who put 160 tires on a Ninja 300 aren't (as) interested in performance. They're doing it for looks.

There's a reason Kawasaki decided to put 110/140 tires on the 300. You don't need more than that for the low-mass of this bike. It doesn't put enough power-down (stock) to require bigger tires, either. The highest I'd recommend is 120/150 (if you insist on going-bigger) but I wouldn't go to a 160 rear.

I upgraded my tires to Pirelli Diablo Rosso IIs and I stuck with the stock sizes: 110/70-17 front and 140/70-17 Rear. They feel great...even when I am going as hard as I am willing to go on the street.
 

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I know people have said to the contrary, but I feel like having a wider tire would make the bike more stable at high speeds, i.e. highway driving. Just logically it seems that way to me. I'm certainly considering doing a 120/150.
 

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well there are many variables, but generally speaking, a wider tire gives you a larger contact area reducing the load and resulting in more traction
A larger tire would create greater mass which would put a greater load on the engine. It would increase traction by increasing the size of the contact patch but that's also what would make it harder to turn in with. That greater contact patch size will require more power and effort to change direction. This is why the 300 handles better and feels much more responsive than a super sport even though they have almost identical wheel bases, trail, and rake. The smaller tire's contact patch doesn't create nearly as much resistance and the smaller wheel wont require as much energy to counteract inertia and momentum. Also keep in mind, just changing the rear tire out for a bigger one without changing the front will alter your rake, trail, and wheel base and if you have ABS, it could screw up the ABS sensor.
 

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A larger tire would create greater mass which would put a greater load on the engine. It would increase traction by increasing the size of the contact patch but that's also what would make it harder to turn in with. That greater contact patch size will require more power and effort to change direction. This is why the 300 handles better and feels much more responsive than a super sport even though they have almost identical wheel bases, trail, and rake. The smaller tire's contact patch doesn't create nearly as much resistance and the smaller wheel wont require as much energy to counteract inertia and momentum. Also keep in mind, just changing the rear tire out for a bigger one without changing the front will alter your rake, trail, and wheel base and if you have ABS, it could screw up the ABS sensor.
im referring to load on the tire, not the engine ahha. Also the coef of friction tells us no matter the surface area, friction will remain constant. Again, variables such as warm or wet pavement come into play.. id have to look this all up again..been awhile ha
 

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I know people have said to the contrary, but I feel like having a wider tire would make the bike more stable at high speeds, i.e. highway driving. Just logically it seems that way to me. I'm certainly considering doing a 120/150.
Sometimes science defies logic or intuition, but that's why physicists and engineers get paid handsomely (and some are better than others).

Motorcycle-engineering is built on years of an understanding of physics, which is under the purview of science and the scientific method. The scientific-method itself is guided by evidence, observation, independent peer-review, verification, falsification, etc., and it's been happening since anyone rode a bicycle or motorized two-wheeler. This knowledge is cumulative. When you buy a motorcycle, you're getting a bit of technology that's incrementally-improved since motorcycles were first-patented in 1868. That improvement has come through innumerable tests and races with new technologies applied to make parts lighter, stronger, cheaper, more-efficient, etc. All the while, the understanding of physics and science itself improves, forging the path for still-better technology applied to everyday items—motorcycles included.

So, a lot of these principles are well-understood. I know it seems 'logical' that a larger tire is more 'stable' at higher-speeds, but remember the context in which your rear tire operates (a light Ninja 300 and not a ZX-10R). Have you seen those little 250cc bikes racing in MotoGP 3? They carry lots of straight-line and corner-speed, with lots of lean-angle and their tires are appropriately-sized for the lower-mass and power of those bikes.

Another point is to understand the difference between the physics of a bike (based on its power and mass) vs. cost-cutting measures applied to its constituent parts.

Cost-cutting measures would be the organic brake pads (also done to be easier on new riders, no-doubt), cheap head-bearings (easily-replaced), etc. Even the IRC stock tires are arguably a cost-cutting measure intended to provide the most cost/benefit for Kawasaki, but not the best grip for aggressive-riders. Of course, those are easily-replaced. The size of the tire is dictated by physics as it applies to a low-mass, 35 HP Ninja 300.

Freelancer explained it nicely, and there are all kinds of write-ups on this topic on the web and in various moto-mags.

When in doubt, trust the engineers who get paid well to understand these things and who will argue with each other if someone gets it wrong or defies best-practices in some way. It's also a good thing you're asking the forum here, because there are some savvy people here who can offer well-informed opinions*.

*Not all opinions are equal, even if we all have them. :D
 

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True, the coef of friction doesn't change due to surface area, but a greater surface area will take more energy to reach that coef due to distribution of load like you said. Otherwise, going to a bigger tire when you have a larger engine wouldn't do anything for you at all. We're pretty much saying the same thing in that regard. Also, engine load increase is very important when a bike has relatively low torque like our bike does. It will really exacerbate load issues like going up hill and starting from a stop and acceleration and will be harder on the engine.
 

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If you're simply commuting, the stock tires are fine. There is nothing wrong with them. I rode through dirt and rocks and didn't lose any traction. All the people with "hate stock tires" posts usually have a malfunction somewhere between the seat and handlebars. :rolleyes:
With that being said, I personally didn't like the look of my stock tires. I went with the Pirelli Diablo ll purely for aesthetic purposes. I went with a 120 on the front and 150 on the back. They feel very planted and I don't have a single negative thing to say about them. They fit very nicely on our rims too. If you're thinking about switching tires, I can tell you, you won't be disappointed with them.
1370376070797.jpg

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The stock tires lack grip and feel on pavement, not dirt and rocks Bran. :eek:

You can say they are fine, but truth be told you give up steering and braking performance with the stock tires and others like them. Doesn't mean you can't use them, just be aware that they limit your performance. Push them too far and expect them to let go, and they do it without warning BTW.

Trouble with thinking it is fine "for commuting" is that you don't get to pick where an emergency stop or swerve will happen. You don't just scratch a bumper like with a crappy car. You end up on the ground, in traffic. Not a great place to be!

I run a 120/150 combo on my 300. They slow steering down just a smidge, but you really can't feel it unless you ride both sizes back to back. I did that several times in a day chasing a steering wobble issue. Having a tire machine is very nice.

The bike is more planted too, but I credit that to the compound, grip and feedback from the better tires, not necessarily the size.
 

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The stock tires lack grip and feel on pavement, not dirt and rocks Bran. :eek:

Ugh.... Really? Let me explain. People have said several times how they felt a slide when running over gravel or dirt. As long as you're not being a dummy, they do just fine.

You can say they are fine, but truth be told you give up steering and braking performance with the stock tires and others like them. Doesn't mean you can't use them, just be aware that they limit your performance. Push them too far and expect them to let go, and they do it without warning BTW.

Simply commuting, there is no reason you should be "pushing" anything.

Trouble with thinking it is fine "for commuting" is that you don't get to pick where an emergency stop or swerve will happen. You don't just scratch a bumper like with a crappy car. You end up on the ground, in traffic. Not a great place to be!

The best of tires can't always save you from that. Riding with plenty of space between you and the car ahead of you helps TREMENDOUSLY with that.

I run a 120/150 combo on my 300. Awesome, me too.

They slow steering down just a smidge, but you really can't feel it unless you ride both sizes back to back.

Same reason you don't own a Camry and jump into a Jag. You'll suddenly notice every shortcoming your ride has.

The bike is more planted too, but I credit that to the compound, grip and feedback from the better tires, not necessarily the size.

Finally! We agree. I never said it was because of the tire size. I absolutely agree it is due to the compound.

Stop arguing with me Fred. This is not the fairing gap thread. :D


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Also keep in mind that you will usually get a taller tire by bumping sizes as the tire width also dictates sidewall height.

Sport Rider did a couple of articles on tires, and even though they were for 180 and 190, the same principle applies if you are looking to go with a wider tire.

http://www.sportrider.com/tech/tires/146_0302_rear_motorcycle_tire/





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Given the weight of our bikes and limited top speed, you are more than likely not going gain any type of performance from a tire wider then our stock size. You will pay more usually for the more tread, and increase the time of side to side movement. Super-moto and off-road bikes can gain some advantages with a little wider tire given what the bike is trying to do on their terrain. Street bikes are good when they can corner faster which means transition speed from one side to the other. Your side contact patch will likely not improve with the wider tire, but a different tire style in the same OEM width could give you more surface area depending on the tire design. Shop around base on tire technology and not size for the best performing tire. Sometimes going smaller can make you faster...
 

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I have heard great reviews about the Michelin Pilot Road 3, but they nearest size to our stock rear tire is 150/70ZR17. Would that be a tire that would be OK on the 300?
Thanks, Cheers
 

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The single biggest benefit of the 150 vs.140 is selection. The only reason I race on the 150 Pirelli Supercorsas is the fact that they aren't available in 140. The 140 Diablo Rosso II's are a great tire, but I like the SC1 and SC2 compounds a little better.

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Discussion Starter #20
If you're simply commuting, the stock tires are fine. There is nothing wrong with them. I rode through dirt and rocks and didn't lose any traction. All the people with "hate stock tires" posts usually have a malfunction somewhere between the seat and handlebars. :rolleyes:
With that being said, I personally didn't like the look of my stock tires. I went with the Pirelli Diablo ll purely for aesthetic purposes. I went with a 120 on the front and 150 on the back. They feel very planted and I don't have a single negative thing to say about them. They fit very nicely on our rims too. If you're thinking about switching tires, I can tell you, you won't be disappointed with them.


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Thanks. That was my other concern. Larger tires fitting the stock rims nicely. :)
 
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