GStwin.com GS500 Message Forum

Main Area => General GS500 Discussion => Topic started by: TXGSF on October 31, 2011, 03:36:48 PM

Title: Tire Question
Post by: TXGSF on October 31, 2011, 03:36:48 PM
Just picked up an 07GS500F and noticed the po rode with the front tire really low 15psi now the tire is cupping. Is this safe to ride on? also i ordered a new tire from Bikebandit.com but ordered a 110/80/17 and the original is 110/70/17 will this be an issue? thanks in advance
Title: Re: Tire Question
Post by: burning1 on October 31, 2011, 03:43:58 PM
It's probably not the end of the world. So long as the tire isn't overly old, cracked, out of tread, super hard, etc... You can probably keep using it.
Title: Re: Tire Question
Post by: gsJack on October 31, 2011, 03:56:36 PM
I've run as many 110/80 front tires as I have 110/70 ones on my GS500s mostly because my local place usually has the 110/80 in stock.  Not much difference in the handling and the 110/80 does make your speedo more accurate.  Tires I've run on my GSs on the stock rims:

http://img.photobucket.com/albums/v443/jcp8832/GS500tirelogs.jpg

Title: Re: Tire Question
Post by: TXGSF on October 31, 2011, 04:18:52 PM
Thanks for the quick replies  :thumb:
Title: Re: Tire Question
Post by: ghostrider_23 on October 31, 2011, 05:10:19 PM
Would someone explain to me tire size like which one is wider.

One of the things I want to do when it's time to replace my tires would be to go with a larger width in the back.
Title: Re: Tire Question
Post by: Big Rich on October 31, 2011, 05:27:46 PM
Take a 110/80-17 tire for example: the "110" is the width in millimeters. The "80" is the height of the tire, but is a percentage of the width (80% of 110mm, so it is 88mm tall). And obviously the 17 is the rim diameter.

Title: Re: Tire Question
Post by: twocool on November 01, 2011, 03:12:37 AM
Quote from: ghostrider_23 on October 31, 2011, 05:10:19 PM
Would someone explain to me tire size like which one is wider.

One of the things I want to do when it's time to replace my tires would be to go with a larger width in the back.

How come?  In bicycle racing, we always looked for the narrowest tire.  Narrow = fast

In motorcycles everybody seems to want fat tire?  fat tire = macho?

In bicycle racing fat tire = dork

just wondering

Cookie

Title: Re: Tire Question
Post by: Bluesmudge on November 01, 2011, 11:42:56 AM
Its because the race bikes need more rear tire on the road to maintain grip with all that hp. Fat Tire = your bike looks more like a moto GP bike I guess. On a GS it just makes the handling worse but a lot of people prefer the look. I have a 140 on the stock rim and its a good compromise. A lot of tires don't come in 130 but do come in 140.
Title: Re: Tire Question
Post by: twocool on November 01, 2011, 12:37:14 PM
What Is The Skinny on Fat Tires? 13 Share October 13, 2010 | By: Jake Herring
Is the fat tire craze over? I think not — but it's definitely showing signs of slowing down. I'd be the first to admit that fat tires look cool on some bikes, but for the most part those bikes are only displayed in shows where they're taken off the trailer and put back on after the show.

I remember back before this tire craze started that if you had a 150mm tire on your bike, it was considered fat.  Did you know there are manufacturers out there today making tires for motorcycles that measure more than 330mm? Unbelievable! My personal opinion is anything over 200mm is overkill — especially if it's on a daily driver. With a tire that big, you can pretty much kiss a motorcycle's handling characteristics goodbye.

In today's world of motorcycle customization, more and more people are building skinny bobbers using stock frames. Maybe it's the fact money is tight and people have limited cash reserves under their mattresses to build a bike from scratch. Or it could be the cost of motorcycle tires, which average about $1 per millimeter of width. Purchasing just one replacement fat tire can be pretty expensive — especially since the average tire only lasts about 5,000 miles, give or take a burnout or two.It's my opinion that a wide tire is built for going straight. A fat tire works great on a drag bike, which needs all of its rubber-to-road contact in order for the bike to hook up and not just sit and spin. But whe

In it comes to practicality and daily use, I just don't see the advantages of a wide tire. Laziness, I can understand. Maybe you want to get off your bike and not use the kickstand. And I suppose some tires or so wide the bike stands on its own. But like I said, other than that, I can't see it.

My personal motorcycles are quick and agile.  It's much easier to lane split or shoot down the breakdown lane with a skinny tire, especially when you're late to work. Unfortunately, I find myself doing both more times than not. Like I said before, the wider the tire, the more you sacrifice handling. Oh, it can be done, but you're going to spend most of your time just fighting the bike from lane to lane. Someone might argue that point, but I ride my bike 60 miles to and from work each day, and I can assure you it's much easier to dip in and out of traffic on a bike that is agile and streamlined.

I'm not saying go out there and buy yourself a plastic crotch rocket, but for a commuter bike or something on which you want to have fun tearing up the road, you'll need to tone down the tire size a little.

I'm a firm believer in "to each his own," so by all means, do whatever floats your boat. Who knows? Some day I might have a fat tire monster in my lineup, but it will be a show bike or a very local bar hopper. For now I'm sticking to my 150mm, and I'll be waving at you as I shoot down the sidewalk on my way to work. Later.....

Title: Re: Tire Question
Post by: ghostrider_23 on November 01, 2011, 12:59:25 PM
So which one is wider 130 or 140
Title: Re: Tire Question
Post by: the mole on November 01, 2011, 02:40:58 PM
Quote from: ghostrider_23 on November 01, 2011, 12:59:25 PM
So which one is wider 130 or 140

Big Rich already posted this:
Take a 110/80-17 tire for example: the "110" is the width in millimeters. The "80" is the height of the tire, but is a percentage of the width (80% of 110mm, so it is 88mm tall). And obviously the 17 is the rim diameter.

Does that give you a clue?        :dunno_black:
Title: Re: Tire Question
Post by: ghostrider_23 on November 01, 2011, 03:00:13 PM
sweet, thank you. sometimes I can be very dense. Might be all the rain!!!!
Title: Re: Tire Question
Post by: the mole on November 01, 2011, 04:25:38 PM
No worries!

+1 to the quote from Jake Herring posted by two cool, I was just driving my old Mitsubishi van home on a twisty bit of road following a guy on a Harley with one those huge tyres on the back, he was leaving me on the straights, but I was catching him on the corners. Those tyres have so little curvature in the cross section that they can't work on lean angles past about 30 degrees. All show and no go.
Title: Re: Tire Question
Post by: ghostrider_23 on November 01, 2011, 05:31:58 PM
What tire size is everyone running :icon_question:
Title: Re: Tire Question
Post by: the mole on November 01, 2011, 05:33:52 PM
130/70x17 BT45 at the moment, but my last one was a 130/80x17 and I marginally preferred the handling with that one.
Title: Re: Tire Question
Post by: Big Rich on November 01, 2011, 06:52:39 PM
Completely irrelevant because it's a different bike, but here's what is on my GR650:

100/90-19 front
110/90-18 rear

Pizza cutters!
Title: Re: Tire Question
Post by: weedahoe on November 01, 2011, 09:46:36 PM
I just bought some really nice used Metzeler Sportec M3s 120/160 (front and rear) off ebay for 65 shipped for the pair. When they got here they looked even better.
Title: Re: Tire Question
Post by: twocool on November 02, 2011, 06:05:44 AM
Quote from: Bluesmudge on November 01, 2011, 11:42:56 AM
Its because the race bikes need more rear tire on the road to maintain grip with all that hp. Fat Tire = your bike looks more like a moto GP bike I guess. On a GS it just makes the handling worse but a lot of people prefer the look. I have a 140 on the stock rim and its a good compromise. A lot of tires don't come in 130 but do come in 140.

You'll find that many say that the width of the tire has nothing to do with the contact area to the road.  In other words a skinny tire and a wide tire on the same bike at the same pressure will have the same contact area!

You will also find many that say a wider tire offers no more "grip" than a skinny tire.  Friction is based on weight, and material, not surface area.

Many also say the the shape of the contact area doesn't matter either...like a long narrow patch, or a short wide patch..

Best reason I can find for wide tires is longer tire life for soft compound tires, since wear is distributed over more tire area.  Basically on a wide tire you get more rubber...so it takes more mile to wear off that more rubber..This then allows for softer compound while still giveing reasonable wear mileage.

So better grip for turning or braking comes from rubber compound, not tire size!

Cookie



Title: Re: Tire Question
Post by: Phil B on November 02, 2011, 10:02:41 AM
Quote from: twocool on November 02, 2011, 06:05:44 AM
You will also find many that say a wider tire offers no more "grip" than a skinny tire.  Friction is based on weight, and material, not surface area.

Many also say the the shape of the contact area doesn't matter either...like a long narrow patch, or a short wide patch..


I would think that, while shape of contact patch does not matter, the strict area of the contact patch, does.
For a variety of reasons.
Note that:

http://www.school-for-champions.com/science/friction_equation.htm

"
In the case where a surface is soft, there is molecular adhesion, and in rolling and fluid friction, the coefficient of friction is not a simple number. The coefficient may be dependent on the area of the surfaces, the amount of deformation, the amount of adhesion, the shape of the surfaces, the radius of the wheel or the viscosity of the fluid.

What this means is that although the standard friction equation holds in these cases, the coefficient of friction will only hold for a specific configuration. In other words, you can't accurately give something like the coefficient of rolling friction for a rubber tire on pavement without stating the type of rubber, area on the pavement, inflation of the tire, and its tread pattern.
"

Do note that "area on the pavement" aka "size of contact patch" is referenced as a factor.

That being said, a wider tire may have more grip, but ironically, lessens your turning ability at the same lean angle, because the curvature of the tire is less.

That is why people tend to keep their FRONT tires narrow, since that affects turning.
Title: Re: Tire Question
Post by: twocool on November 02, 2011, 11:17:08 AM
Quote from: Phil B on November 02, 2011, 10:02:41 AM
Quote from: twocool on November 02, 2011, 06:05:44 AM
You will also find many that say a wider tire offers no more "grip" than a skinny tire.  Friction is based on weight, and material, not surface area.

Many also say the the shape of the contact area doesn't matter either...like a long narrow patch, or a short wide patch..


I would think that, while shape of contact patch does not matter, the strict area of the contact patch, does.
For a variety of reasons.
Note that:

http://www.school-for-champions.com/science/friction_equation.htm

"
In the case where a surface is soft, there is molecular adhesion, and in rolling and fluid friction, the coefficient of friction is not a simple number. The coefficient may be dependent on the area of the surfaces, the amount of deformation, the amount of adhesion, the shape of the surfaces, the radius of the wheel or the viscosity of the fluid.

What this means is that although the standard friction equation holds in these cases, the coefficient of friction will only hold for a specific configuration. In other words, you can't accurately give something like the coefficient of rolling friction for a rubber tire on pavement without stating the type of rubber, area on the pavement, inflation of the tire, and its tread pattern.
"

Do note that "area on the pavement" aka "size of contact patch" is referenced as a factor.

That being said, a wider tire may have more grip, but ironically, lessens your turning ability at the same lean angle, because the curvature of the tire is less.

That is why people tend to keep their FRONT tires narrow, since that affects turning.
I've seen this arguement...and seen both sides...that rubber is somehow "magical" compared to other substances when it comes to friction...hmmmm.....

Possibly a good arguement for contact area....but a wider tire does not give this....Contact area is same...wide or skinny........

Only way for more contact area is to put heavier weight, or less  tire pressure.....but you can do this with fat or skinny!

Now about the "front wheel does the turning"....hmmm.....then how do I turn on my unicycle???  (or doing a wheelie on my bike??)

Cookie
Title: Re: Tire Question
Post by: mister on November 02, 2011, 12:02:14 PM
110 front
140 rear (cause they didn't have any 130 in stock)

Michael
Title: Re: Tire Question
Post by: Phil B on November 03, 2011, 09:37:50 AM
Quote from: twocool on November 02, 2011, 11:17:08 AM

Now about the "front wheel does the turning"....hmmm.....then how do I turn on my unicycle???  (or doing a wheelie on my bike??)

Cookie

Those are silly, yet related questions.

on a unicycle, "the" wheel is, literally and logically, the front wheel.
Just like an only child, is also "the oldest child", "the favourite child", etc, etc.

if you do a wheelie, then you turn your moto into a unicycle, that just happens to have a useless circular appendage in the upper regions.
Title: Re: Tire Question
Post by: burning1 on November 03, 2011, 02:23:47 PM
In empirical testing, it was demonstrated that a wider tire would produce *slightly* more grip than a narrow tire; we're talking a few percentage points for going from a 160 to a 180. For a racer a few percentage points is huge, since it can mean a second/lap difference. To the street rider, not so much. Tire compound has a significantly greater impact on traction.

See Motorcycle Dynamics by Vittore Cossalter for details.

In practice, there are some significant downsides to running too wide a tire, especially when we're talking about the massive 300mm+ ones seen on some cruiser bikes.

Larger tires are heavier, which means less un-sprung weight, more rotational inertia, and more gyroscopic resistance to turn in. The profile can be a little flatter, which also creates resistance to turn in (was a major issue with early 190/50/17 tires.)

In general, 110/70/17 & 140/70/17 profiles seem to work extremely well on the GS500. You can run a 150 rear bias ply tire on the GS, but I'd recommend running a radial larger than 140. For race use, a number of manufacturers make 110 fronts. The BT003RS rear tire works extremely well on this bike, and plays nicely with the fronts from other brands. Pirelli is also working on a Diablo Rosso 2 tire in those sizes; Brian Bartlow was testing it out this weekend at Sears Point.

For race use, we sometimes install larger rims because we want more tire options. For street riders, it's a non issue; there are tonnes of good street tires designed to fit the stock rims.

In general, I'd suggest not trying to 2nd guess the engineers that designed the bikes. Modding can be fun, but usually impractical.
Title: Re: Tire Question
Post by: scratch on November 03, 2011, 02:40:20 PM
Give me skinny tires in the rain!

I'm currently running the Avon RoadRunners in 110/70 and 130/70 for the quick turning, chassis attitude and bottom end (without the sprocket change).  Great for the Rain!
Title: Re: Tire Question
Post by: twocool on November 03, 2011, 03:31:59 PM
Let's face it...most guys are putting on bigger tires because they think it "looks cool".

In USA the motto (for everything) is always "bigger is better" and the "bigger the better"

When you ask "why", you dont' get good answers, except,   "It has to be better, It's bigger!"

My motto is "better is better"..........

Throuble is with most things there is always a trade off......better in one respect and not better in another.....so you have to compromise.

But it is a free country..so if you want fat tires...get fat tires......at least you'll "look" cool.


Cookie