rear tire, 190/55 or 190/50 whats the difference?

[rtarp1]

Im an aggressive rider , which rear tire do i want?

[Jeremy Mitchell]

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. 

[jjsC6]

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.

[rtarp1]

thanks for the help guys . 

[TRBN]

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

[Conrad]

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.

[gonzosc1]

+1, I'd like to hear (read) this explained as well.

+2

[B.D.F.]

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. 

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>

[B.D.F.]

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

[Wile]

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

[VirginiaJim]

I know this is a little late but .......   5?

[Kirby]

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

[B.D.F.]

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?

[VirginiaJim]

Sigh....

[B.D.F.]

Right back at 'cha. I am going to have to use more smileys....

Brian

Sigh....

[DaveO]

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.

[VirginiaJim]

Right back at 'cha. I am going to have to use more smileys....

Brian

No need.... 

[B.D.F.]

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.

[jjsC6]

....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. 

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).

[B.D.F.]

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

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?   

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).