Some Tire info - Ex-500.com - The home of the Kawasaki EX500 / Ninja 500R
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post #1 of 14 (permalink) Old 1-25-2007, 12:52 PM Thread Starter
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Some Tire info

Tires:

A Little word that you can write volumes about:

Where to start? In these Forums, a tire thread usually goes on for 4 pages with nothing more than subjective opinions or old wives tales centered on Brand loyalty. Nobody seems to have even a modicum of knowledge about tires.
I thought that some hard facts may help you when you think about tires or handling problems.
Were going to keep in Laymanís terms here not scientific stuff or formula.

Traction: hey thatís what tires are all about right? Part of the traction a tire gives is simply the CF (coefficient of Friction) that a particular compound gives. This can vary slightly. There is virtually no difference in CA of any compound normally used in street tires.
Most of the differences in traction of various rubber compounds comes from the hardness of the rubber. This is measured by indenting the rubber with a spring loaded devise and measuring the depth of the indentation. This ďDepthĒ is then transcribes on a Durometor Scale There are several scales, the one that covers tires it the ďDĒ Scale. A given tire rubber compound will measure from around 50 to 100 D. The higher number the harder. You wonít find the number on any tires but most car tires have a Wear factor number that runs from 100 to 1000 with the higher being the longest wearing. This number is not solely a hardness number alone, but thatís most of it.

Why the hardness of a tire relates so much to the traction limit of that tire is because most of the grip of a tire on the road is from the rubber deforming around the road surface irregularities. Not the CF of the rubber. So the softer the rubber the more it deforms, the more grip. Itís not hard to imagine that there are real limits to how far you can go in either direction. Too soft and the tire wears rapidly or chunks, too hard and it doesnít grip at all. BTW this is why motorcycles can lean past 45Deg.

Ok up to now we havenít talked about tire construction. This is also related to traction. (Well hell everything about a tire (except white walls) is related to traction).
There are three fundamental types of tire constructions. The cross Bias, The Belted cross Bias. And the Radial.

The difference lies in the way the strengthing cords are arranged (all tire have cords)
Cross Bias: this is the oldest type. The cords run from one bead or edge to the other on an angle and each layer crosses the first in the opposite angle. This produces a tire that flexes uniformly across it entire surface.

The Bias belted: Constructed as the Cross Bias, with the addition of a stiffer circumferential bead or Breaker. This give a tire with Dual flexing rates. The breaker stiffens up the tread to reduce it deformation under load, but the side walls remain more flexible

The Radial: In this tire the cords are laid at a 90 degree angle in respect to the centerline of the tire and there is no crossing, Then a strong Breaker (usually steel Mesh) in laid under the tread, virtually eliminating any tread flexing at all. The side wall must then be very flexible.

Slip Angles: This is the angle of the difference between the direction the wheel is pointed in and the actual direction of travel of the machine. Or a fair estimate of the degree of sliding.

First let me say that this is not a racer thing or something confined to hard riding near the limit of adhesion. Every tire on every machine generates a slip angle when turned. A couple of forces cause this. The natural histories of the rubber (you know, the spring back) and the construction of the tire cords. Bias tire have more self aligning torque than radials and conversely generate greater slip angles.

Tire pressure can increase /decrease the slip angle of a given tire
Watch NASCAR? When you hear the commentators talk about the carís pushing, or is loose/tight. Then he went up/down Ĺ lb. in the rear to fix it. What they were doing is adjusting the slip angle of the tires with tire pressure.

OK on any vehicle: a rear with a greater slip angle than the front will tend to tighten a given turn. If this is severe the thing could be un rideable. This is the reason that youíll always be warned that it is un wise to mix tire brands. Especially Radial and Bias types.

There are a few thousand more points that affect how tires perform, but they are off into the area we donít need to get to.

Think about all of the above the next time youíre buying tires or have a handling problem, some of it may help.

FOG

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post #2 of 14 (permalink) Old 7-21-2009, 8:10 PM
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Re: Some Tire info

Good writeup. I think this should be stickied, but probably in the Tire forum and not the DIY forum.
post #3 of 14 (permalink) Old 3-16-2010, 9:44 PM
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Re: Some Tire info

Seriously. Its spelt "tyre".
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post #4 of 14 (permalink) Old 3-16-2010, 9:52 PM
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Re: Some Tire info

Quote:
Originally Posted by CobbZ
Seriously. Its spelt "tyre".
Depends where you live. Tyre in UK, Tire in North America. Kinda like color and colour.

type signature here...
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post #5 of 14 (permalink) Old 3-28-2010, 9:50 AM
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Re: Some Tire info

Quote:
Originally Posted by twowheels
Quote:
Originally Posted by CobbZ
Seriously. Its spelt "tyre".
Depends where you live. Tyre in UK, Tire in North America. Kinda like color and colour.
So what you're really saying is that in England, and therefore in the English Language, it's spelt tyre! Lol.[/color]


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post #6 of 14 (permalink) Old 5-21-2010, 4:22 PM
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Re: Some Tire info

Quote:
Originally Posted by Tommy H
Quote:
Originally Posted by twowheels
Quote:
Originally Posted by CobbZ
Seriously. Its spelt "tyre".
Depends where you live. Tyre in UK, Tire in North America. Kinda like color and colour.
So what you're really saying is that in England, and therefore in the English Language, it's spelt tyre! Lol.[/color]
I dont know bout all that fancy spelling but i know we dont like none of em down here in the south.
post #7 of 14 (permalink) Old 5-21-2010, 5:18 PM Thread Starter
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Re: Some Tire info

Stop corrupting this Sticky with this stupid crap.

FOG
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post #8 of 14 (permalink) Old 4-6-2011, 10:20 AM
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Re: Some Tire info

Wow FOG, thanks for this excellent writeup. A must read for anyone thinking about tires or tyres!

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post #9 of 14 (permalink) Old 6-22-2011, 5:44 PM
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Re: Some Tire info

The air valve on my front rim is leaking. Is that something I can easily do myself with out screwing it up? Or is it something I should just pay to have it done because it's better to have a professional do it? (i.e. mounting and balancing tires)
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post #10 of 14 (permalink) Old 6-22-2011, 6:05 PM Thread Starter
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Re: Some Tire info

you can replace the core easy. They just un screw. But if it's the seal to the rim .You need to fit a new valve. They pull through from the inside and of course require the bead to be un seated.

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post #11 of 14 (permalink) Old 5-31-2013, 11:38 PM
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Re: Some Tire info

yah this is great info here, thanks FOG.

I just hit 6k on my rear which is an IRC and have now hit the little indicator "lump?" so I'm going in this tuesday to put on a Bridgestone BT-45 to match the front. This is my first bike and I bought it like this from the dealer. I probably wouldn't have ever thought about matching the brand... Never did with any of the cars/trucks I've owned.
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post #12 of 14 (permalink) Old 11-5-2014, 10:39 PM
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Re: Some Tire info

just a bit of worthless advice ...I mostly pump my tyres up at petrol stations which is problematic because the hose end that fits onto the tyre valve wont fit and can take a while to get it on so buy a valve extender to save time and energy
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post #13 of 14 (permalink) Old 8-19-2015, 5:40 PM
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Re: Some Tire info

Thank you for the brief informative basics of a very technical subject.
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post #14 of 14 (permalink) Old 8-20-2015, 8:43 AM
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Re: Some Tire info

Thanks FOG, good post and even though it is 8.5 years old, it all rings true today. Tire technology is not rocket science but was a mystery to me for many years and this straight to the point explanation is very useful to know.

Current ride: 2014 Triumph Rocket III Touring; 2007 EX 500R; 1981 XS650SH in resto
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