Kawasaki Concours Forum
The C-14, aka Kawasaki Concours-14, the new one :) => Accessories and modifications - C14/GTR 1400 => Topic started by: rtarp1 on October 26, 2011, 08:56:54 AM
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Im an aggressive rider , which rear tire do i want?
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The taller profile of the 190/55 gives quicker turn in and there is also more rubber in contact with the road while you are leaned over which give me more confidence in the corners. I noticed a huge difference when I switched, I will never go back to 190/50.
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The taller profile of the 190/55 gives quicker turn in and there is also more rubber in contact with the road while you are leaned over which give me more confidence in the corners. I noticed a huge difference when I switched, I will never go back to 190/50.
I agree, but I can't wait for Brian's explanation of how the contact patch will actually be the same (Brian - you know I just have to bust your balls on that).
The real advantage for street riding is simply the responsiveness of the bike. And I do agree with jeremy that you will feel a lot more confident. I find myself touching the foot pegs not realizing how much faster I'm taking curves just because the bike feels so much better that I don't feel like I'm pushing as hard as I am.
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thanks for the help guys .
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I agree, but I can't wait for Brian's explanation of how the contact patch will actually be the same (Brian - you know I just have to bust your balls on that).
Actually, why would the profile of the tire be that different? The 50 or 55 is just the sidewall height in ratio to its width. Why would that change the contact patch?
Aaron
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Actually, why would the profile of the tire be that different? The 50 or 55 is just the sidewall height in ratio to its width. Why would that change the contact patch?
Aaron
+1, I'd like to hear (read) this explained as well.
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+1, I'd like to hear (read) this explained as well.
+2 8)
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Not mine, Newtonian physics: F = P/A. The Force (in pounds) on the tire which is both the overall weight as well as any cornering / braking / accelerating forces on the tire will equal the Pressure (in PSI) divided by the Area (in square inches) of tire in contact with the ground. The contact patch area will be the same given the same force and pressure no matter what the tire's size (within reason of course- let's not use model car tires as an example). Certainly between a 190 / 50- 17 and a 190 / 55 - 17 mounted on the same wheel.
I never said the contact patch would not change, I said the contact patch area will not change.
Here is a quick and easy test you can try at home: measure the area in contact with your driveway with the tire at normal inflation pressure (a tape measure is good enough here). Now let out air until the tire is at 1/2 the original pressure and again measure the area in contact with the driveway- betcha' it doubles (if P is cut in half, A must double to compensate for the same F).
Besides Jim, I do not respond to these threads for you as you have convinced me you believe otherwise and are not interested in reviewing your beliefs on this matter. I respond only for those who may be reading and want a logical, truthful reason as to how contact patch area varies in relationship to other physical changes. See my signature quote for a full explanation. ;D
Brian
I agree, but I can't wait for Brian's explanation of how the contact patch will actually be the same (Brian - you know I just have to bust your balls on that).
<snip>
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The contact patch will be a different shape but the same area given the same pressure inside the tire.
The higher the aspect ratio, the taller the tire for the same bead diameter and wheel thickness. So as the height increases, the radius must get smaller. The contact patch shape will change and become shorter (in the direction of the bike's travel) but wider. Also, the contact patch location will change in relationship to the centerline of the bike.
The big difference is that the tire will have a sharper cross- section so that turn- in is faster. The bike will roll away from the centerline of the tread more easily because the tread center is higher (speaking of a 55 aspect ratio vs. a 50 aspect ratio here).
As an example, picture a piece of paper 10 inches long, bent into a radius so that the edges of the paper were on a desk and spaced 5 inches apart- the paper would take on a given radius. Now put an 11" piece of paper's edges down on the desk again spaced to 5"- the radius has no choice but to get smaller and the height of the curved paper will get higher. This is what is happening with an increasing aspect ratio of a tire on a motorcycle (it does NOT apply to cars as they have a flat section).
Brian
Actually, why would the profile of the tire be that different? The 50 or 55 is just the sidewall height in ratio to its width. Why would that change the contact patch?
Aaron
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As an example, picture a piece of paper 10 inches long, bent into a radius so that the edges of the paper were on a desk and spaced 5 inches apart- the paper would take on a given radius. Now put an 11" piece of paper's edges down on the desk again spaced to 5"- the radius has no choice but to get smaller and the height of the curved paper will get higher. This is what is happening with an increasing aspect ratio of a tire on a motorcycle
Now I understand it but does it really work or is it just Imagineering
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I know this is a little late but ....... 5?
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No, it really does work. It is commonly accepted amongst rodents that we statistically have a 4.3% greater chance of survival when crossing the road in front of a motorcycle if that motorcycle is equipped with a [higher than normal] aspect rear tire. So please, if not for yourselves, do it for us.... Then again, there is absolutely no data on which tires work better on motorcycles equipped with the much- loved KiPass. <shiver>
Kirby
Now I understand it but does it really work or is it just Imagineering
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Yes, percent. The difference is 5 percent. A 50 aspect ratio tire is 50% as high as it is wide, while a 55 aspect ratio is 5% taller (all speaking of cross- section here, not overall tire height).
Brian
I know this is a little late but ....... 5?
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Sigh....
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Right back at 'cha. I am going to have to use more smileys....
Brian
Sigh....
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if you are looking for performance,not posing get a 180/55 .
The tall profile but not as heavy. The c-14 does not need more unsprung weight.
Also less expensive.
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Right back at 'cha. I am going to have to use more smileys....
Brian
No need.... :)
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I have been waiting for someone to honestly try both a 180 / 55 and a 190 / 55 (assuming they have also used a 190 / 50 which is the stock size) in the same tire and give some feedback. Several people have reported being very happy with the 180 on a C-14 but I would think the tire would be flattened out slightly (less round) due to the wider wheel used on a C-14 compared to and FJR or K1300GT, both of which use a 5 1/2" wide tire (6" wide on the C-14).
We can all guess as to what effect the wider wheel will have on the tire's performance but I am looking for real experience.
Brian
if you are looking for performance,not posing get a 180/55 .
The tall profile but not as heavy. The c-14 does not need more unsprung weight.
Also less expensive.
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....Besides Jim, I do not respond to these threads for you as you have convinced me you believe otherwise and are not interested in reviewing your beliefs on this matter. I respond only for those who may be reading and want a logical, truthful reason as to how contact patch area varies in relationship to other physical changes. See my signature quote for a full explanation. ;D
Brian
I won't turn this into another debate, but I do have to respond to what I underlined. I actually have done some more homework on the subject. I asked for opinions elsewhere and I read a number of articles and "white papers" that I found on-line. I'm not even going to discuss what I found out and what I believe. Turns out that I'm not the only one who comes across as not interested in reviewing beliefs ;) (not aimed at you necessarily, I found that to be the case everywhere I turned).
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Er, I think only one of us has said "I still don't believe it and never will." regarding tire pressure as it relates to contact patch area.
http://www.zggtr.org/index.php?topic=2510.msg28861#msg28861 (http://www.zggtr.org/index.php?topic=2510.msg28861#msg28861)
As always, I am more than willing to listen to any other thoughts on this, or any other subject. But as things stand, and given my understanding of the universe we all live in, and of course within some limiting parameters, tire contact patch area is a function of the vehicle's weight on that tire and the pressure inside that tire. When someone says that moving from a 190/50 to a 190/55 alone increases tire contact area, I will beg to differ.
How's about we talk about oil next? ;D
Brian
I won't turn this into another debate, but I do have to respond to what I underlined. I actually have done some more homework on the subject. I asked for opinions elsewhere and I read a number of articles and "white papers" that I found on-line. I'm not even going to discuss what I found out and what I believe. Turns out that I'm not the only one who comes across as not interested in reviewing beliefs ;) (not aimed at you necessarily, I found that to be the case everywhere I turned).
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Not mine, Newtonian physics: F = P/A. The Force (in pounds) on the tire which is both the overall weight as well as any cornering / braking / accelerating forces on the tire will equal the Pressure (in PSI) divided by the Area (in square inches) of tire in contact with the ground. The contact patch area will be the same given the same force and pressure no matter what the tire's size (within reason of course- let's not use model car tires as an example). Certainly between a 190 / 50- 17 and a 190 / 55 - 17 mounted on the same wheel.
I sorta agree here but you have use tire of same carcass construction for that statement to be true..
190/50 as opposed to 190/55 would be different construction no??
It has a different shape...
I think a tire with different profile could put more rubber on the road at certain lean angles even using same psi
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I will add my 2 cents here, take it or leave it.
I ride very aggressively and with the 190/50 I had ZERO chicken strips, which told me I was possibly getting to the point of not having much rubber in contact with the road when running at my max lean angle. With the 190/55. I have somewhere between 1/16 and 1/8 of an inch left on the side, that tells me that the tire has more rubber left in reserve when I am at the same max lean angle.
The amount of rubber in contact with the road is debateable like BDF stated but for me I can see an improvement. My best advice is just to try a 55 and see for yourself. If you don't like it just sell it to me and go back to a 50.
;D
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Yes, there are other factors such as the tire carcass stiffness and the tread. But the overriding factor is still the internal pressure, especially so when considering two tires that are identical other than the aspect ratio. Again, a common belief is that changing a tire to a higher aspect ratio changes the amount of rubber in contact with the road is just not correct.
A toy balloon would act more like a perfect vessel than a vehicle tire regarding the pressure / area function. For example, all the stiffness in a balloon comes from internal pressure only- bring that pressure to zero and the balloon really will lay flat. The same is not true for a tire of course, even without pressure there is enough stiffness in a tire to hold it upright and hold its shape. So yes, there are other factors and they must all be considered; it is certainly not universally simple and true that contact patch area is a function of internal pressure alone but it is the predominant factor.
As far as tire shape goes, again that will be overridden by the pressure / area relationship. If the shape of the tire is brought more toward a triangle in an effort to increase patch area, and the same internal pressure is used, the actual result will be that the patch is wider but shorter (in the direction the motorcycle travels). Even a clever designer cannot outsmart or outrun physics.
One obvious example of other forces would be the way wrinkle- wall tires act when used in drag racing. The contact area is a function of the internal pressure (which is extremely low to use a lot of contact patch area) at first but then centripetal force must be factored in. With the vehicle sitting there the tires appear almost flat but once the tire is spun up to high speed, it becomes much more round and much larger in diameter as well as narrower. The back end of the vehicle is raised up quite a bit- it is not a subtle effect. I do not know but suspect that the contact patch area changes with this great increase in centripetal force. Of course such things are hard to duplicate on street vehicles, not to mention that fantastic acceleration is never used when a motorcycle is leaned well over in a curve so it is irrelevant.
The short version is this example: if you replace a Michelin PR3 190/50- 17 with a Michelin PR3 190/55- 17 and like the taller tire better, I betcha' it ain't 'cause of the idea that the contact area changed (assuming the same tire pressure is used!).
Brian
I sorta agree here but you have use tire of same carcass construction for that statement to be true..
190/50 as opposed to 190/55 would be different construction no??
It has a different shape...
I think a tire with different profile could put more rubber on the road at certain lean angles even using same psi
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Yep, the taller tire may well work better. Again, my only point was that any change noted is not because the contact patch area changed as long as the same internal pressure was used.
I never meant to imply in any way that a different aspect ratio tire would not perform differently. In fact, I am quite sure they do although I have not tried a 55 on a C-14 yet. I would really like to try a 180/55 as they are lighter and less expensive.
So many choices, so few tire donations.... ;D
Brian
I will add my 2 cents here, take it or leave it.
I ride very aggressively and with the 190/50 I had ZERO chicken strips, which told me I was possibly getting to the point of not having much rubber in contact with the road when running at my max lean angle. With the 190/55. I have somewhere between 1/16 and 1/8 of an inch left on the side, that tells me that the tire has more rubber left in reserve when I am at the same max lean angle.
The amount of rubber in contact with the road is debateable like BDF stated but for me I can see an improvement. My best advice is just to try a 55 and see for yourself. If you don't like it just sell it to me and go back to a 50.
;D
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I have a set of lightly used 021's (10,000 miles) that I'll send ya for the cost of postage ;)
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I have a set of lightly used 021's (10,000 miles) that I'll send ya for the cost of postage ;)
:rotflmao:
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I will add my 2 cents here, take it or leave it.
I ride very aggressively and with the 190/50 I had ZERO chicken strips, which told me I was possibly getting to the point of not having much rubber in contact with the road when running at my max lean angle. With the 190/55. I have somewhere between 1/16 and 1/8 of an inch left on the side, that tells me that the tire has more rubber left in reserve when I am at the same max lean angle.
The amount of rubber in contact with the road is debateable like BDF stated but for me I can see an improvement. My best advice is just to try a 55 and see for yourself. If you don't like it just sell it to me and go back to a 50.
;D
I agree - my results are the same.
Brian - we're still good. No need to open a new debate on oil just to put the tire issue behind us, but if you DO want to discuss oil..... :o
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one more thing puzzles me...changing tire size does what to the accuracy of the speedometer
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Well, I didn't get very far, but the first article I read agrees with Jim. http://www.performancesimulations.com/fact-or-fiction-tires-1.htm (http://www.performancesimulations.com/fact-or-fiction-tires-1.htm)
Since we are not dealing with perfectly elastic substances, it appears that contact patch area, not just shape, depends on much more that merely vehicle weight and tire pressure.
And I did appreciate the humor in the thread: "As always, I am more than willing to listen to any other thoughts on this, or any other subject."
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one more thing puzzles me...changing tire size does what to the accuracy of the speedometer
Increasing rear tire diameter will increase actual speed in relation to indicated speed. Most C14 speedo's read fast, so switching to a 190/55-17 will reduce the speedo error in most cases.
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one more thing puzzles me...changing tire size does what to the accuracy of the speedometer
With the 50 the speed was off 3-4 mph at 70, with 55 is within 0.5 mph versus GPS.
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With the 50 the speed was off 3-4 mph at 70, with 55 is within 0.5 mph versus GPS.
But once you get that Texas highway flat spot down the center ... ...
New, my stock tires yielded about 4-5% error lower than actual (indicated 84 at GPS 80).
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If the contact patch is the same area, but is wider in the bead-to-bead direction while in a lean with the taller tire, does the longer length of the contact patch yield less "slip" in the lean?
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Clyde you charming devil you.... glad to see you back. Can I safely assume you have finished downloading that manual and now have more time for the forum?
;D ;D ;D
Brian
<snip>
And I did appreciate the humor in the thread: "As always, I am more than willing to listen to any other thoughts on this, or any other subject."
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I do not know but it is an interesting question.
Smooth surfaces create friction without regard to the area in contact. For example, smooth steel against steel will have a certain coefficient of friction that does not change with area. Rubber tires on asphalt or concrete is different; the tire is soft and will deform to dip into the little pores of the road surface, so increasing area increases friction. I don't know if changing the shape of a given area changes friction but cutting slices into tread blocks so that they might move independently does. As that is odd behavior, perhaps there are better and worse contact shapes for better or lesser traction?
Brian
If the contact patch is the same area, but is wider in the bead-to-bead direction while in a lean with the taller tire, does the longer length of the contact patch yield less "slip" in the lean?
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So far no one has mentioned the fact that a 55 aspect tire raises the rear, affecting steering geometry. I suggest that this has more to do with any handling improvement than contact patch size and/or shape.
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So far no one has mentioned the fact that a 55 aspect tire raises the rear, affecting steering geometry. I suggest that this has more to do with any handling improvement than contact patch size and/or shape.
I think you nailed it. (although it is a very interesting discussion so far)
I usually change front and rear at the same time. With the first two sets (the original BS) the front was more wasted than the rear, and the last two sets (Angels) it was the other way around (as it is more usual) but they were still similarly worned out.
But last week, seeing that the front still had lots of thread and is round (no cupping) I decided to change only the rear. When the tire was out of the wheel, I compared it with the new one before being mounted and could appreciate the huge change in profile and what astonished me more was the difference in weight between the two. I wish I weighed them, but I bet is next to a pound.
Anyway, I immediately thought that the tail (and only the tail) of the bike would be higher now, and indeed the first thing I noticed when I drove off if how the steering got a tad more responsive (less rake angle). A quick calculation, assuming 59,8 inches wheelbase and 0,2 inches more radius on the new tire, shields a 0,19° less rake angle. And that is noticeable.
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So far no one has mentioned the fact that a 55 aspect tire raises the rear, affecting steering geometry. I suggest that this has more to do with any handling improvement than contact patch size and/or shape.
It will only raise the rear about 1/4 inch, I think the taller profile combined with raising the rear is the reason it works so well. A symbiosis of sorts.
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gotta' love a tire thread. who mentioned on this forum that the 190/55 is a better performer way back when Michelin 1st introduced it heh millions have tried it and verified the difference since ;D
old news, if you don't understand why the 55 performs better pay the 10 bux extra and try one. that simple. but the physics class and debates have been interesting.
tire threads rule! next we need afresh flying luggage thread, with directions for pinning and available aftermarket parts to prevent this phenomenom :D
the 190/55 will turn in quicker.
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gotta' love a tire thread. who mentioned on this forum that the 190/55 is a better performer way back when Michelin 1st introduced it heh millions have tried it and verified the difference since ;D
old news, if you don't understand why the 55 performs better pay the 10 bux extra and try one. that simple. but the physics class and debates have been interesting.
tire threads rule! next we need afresh flying luggage thread, with directions for pinning and available aftermarket parts to prevent this phenomenom :D
the 190/55 will turn in quicker.
Dang Steve! You're slipping man, a post without how many trouble free miles you currently have on your bike?
Maybe it's not really you and someone hacked in to your account, perhaps a pod Steve?
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And no pictures of wimminz and no mention of anything containing the word Honda.... I think you are right Conrad, 'New Steve' is an alien.
I wonder how bit the fob is for a space ship?
Brian
Dang Steve! You're slipping man, a post without how many trouble free miles you currently have on your bike?
Maybe it's not really you and someone hacked in to your account, perhaps a pod Steve?
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And no pictures of wimminz and no mention of anything containing the word Honda.... I think you are right Conrad, 'New Steve' is an alien.
I wonder how big the fob is for a space ship?
Brian
Do you think that the fob for the ship would use a CR2025?
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Do you think that the fob for the ship would use a CR2025?
Nope, it would be run by the power of positive thinking (or fecetious comments). Just like non-alien Steve's bike. ;D
Yes I did use the same play on words before you criticize me for overuse of a mispelled word.
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I've never criticized you have I Jeremy? :-X
I know the word, seen it before you used it in fact.
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Not saying you would criticize, that was just in general.
It is the word of the week so I try to use it at least once a day. ;D
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Not saying you would criticize, that was just in general.
It is the word of the week so I try to use it at least once a day. ;D
Around here, I'd say that it's more like the word of the year. ;)
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So far no one has mentioned the fact that a 55 aspect tire raises the rear, affecting steering geometry. I suggest that this has more to do with any handling improvement than contact patch size and/or shape.
You really think raising the rear 1/8" makes a difference?
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Dang Steve! You're slipping man, a post without how many trouble free miles you currently have on your bike?
Maybe it's not really you and someone hacked in to your account, perhaps a pod Steve?
My mistake, I figured when Michelin PR3s or KiPass is mentioned in a post, everything else is muted anyway. I'll try and do better I promise! ;D
My bike is up in the Carolinas from Tampa today, pushing 45,000 carefree miles in 20 months. Chilly up here compared to FL!
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You really think raising the rear 1/8" makes a difference?
Absorutely. But somebody said it was 1/4 inch". Do you realize that is mor than 6 million meters?
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;D
Brian
Absorutely. But somebody said it was 1/4 inch". Do you realize that is mor than 6 million meters?
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Yeah, good word and all but let's not forget 'gashole' which is probably the word of the decade.
Brian
Around here, I'd say that it's more like the word of the year. ;)
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I'll let you know after Saturday morning. Taking the Battlecracks off and putting PR3's on with a 55 rear Saturday morning.