The Subaru SVX World Network   SVX Network Forums
Live Chat!
SVX or Subaru Links
Old Lockers
Photo Post
How-To Documents
Message Archive
SVX Shop Search
IRC users:

Go Back   The Subaru SVX World Network > SVX Main Forums > Technical Q & A

Reply
 
Thread Tools Display Modes
  #16  
Old 01-15-2003, 06:23 AM
Paisan Paisan is offline
Registered User
 
Join Date: Jul 2002
Location: North Jersey
Posts: 684
Send a message via AIM to Paisan Send a message via Yahoo to Paisan
Quote:
Originally posted by LarryIII
Ron,

I always thought the speed rating is based on a tires ability to resist and disipate the effects of internal heating which causes the tire to debond and come apart. Since tires flex there is a lot of heat generated inside the carcass.
To the best of my abilities, this is what the speed rating is indicating.

-mike
__________________
'14 Touareg TDi | '04 Nissan Armada LE | '14 BRZ
http://AZPInstalls.com
Reply With Quote
  #17  
Old 01-17-2003, 12:11 AM
AbdominalSnoman
Guest
 
Posts: n/a
I thought speed rating had everything to do with simply the tires being able to stand up to all of that centrifugal force (centripetal force? I never remember which one is right)

your lateral acceleration is V^2 / R and if you're going 150mph (67meters / second) and assuming your tires have a stock circumfrence your radius is going to be .315m your lateral acceleration is 14,231 m / s^2 (one G is 9.81 m / s^2) so this is going to be roughly 1400 times as strong a outward force on the tires as gravity exerts on us. The only way that I can think of being able to take this much stress is if they are very light and have very strong re-inforcing materials in them.
Reply With Quote
  #18  
Old 01-17-2003, 05:29 AM
LarryIII LarryIII is offline
Senior Member
 
Join Date: Mar 2001
Location: Wilmington, DE
Posts: 5,791
Send a message via Yahoo to LarryIII
Registered SVX
Abdominal,

You are partially correct in all the things you say. You would be totally correct if the tire operated on a machine that kept it perfecly round as it spun the tire.
However, the tire sits on the ground (road) and must deflect to flatten out as the tread touches the groundand rebound as it leaves the ground. There are also side forces on a tire induced by turning and the cars suspension. All this movement generates flexing and squirm. This causes heat because the carcas of a tire is not one homogeneous piece. It is made up of rubber compounds(synthetic), fabric or metal belts, and fabric cords. Also the tire is built up in plys then molded into one piece. All these materials have different coeficients of strength and expansion.
Think of the inside of a tire as the layers of lasagna rolled into a circle instead of laying flat.

The flexing and squirming that a tire goes through generates heat and rubber is not a good conductor so the heat stays inside the carcas. This internal heat makes the metal, rubber, synthetic fabrics want to expand at different in different rates and in different directions. These pieces try to move in relation to one another. They are not allowed to do this. If they do ...goodbye tire.

The faster you go, the quicker the flexing and squirming takes place, and the more internal heat is generated. Therefore, better materials that are stronger and resist heat buildup better are required. That's why, as the speed rating goes up, the tires cost more.

This is a very simple general explanation. In reality, it's much more complex.
__________________
Larry III & The Beautiful Naviguesser
'19 Tungsten Pearl Outback 3.6R Ltd...."AISHA"
'08 Harvest Gold Outback 3.0L. L. L. Bean...."AIJOU"
'07 Gray Diamond Pearl Outback XT Ltd..."AH SO"
'05 White Pearl & Silver BAJA Turbo..."AH HA"
'97 Bordeaux Pearl SVX LSi..."SUBYDOO"
'94 White Pearl SVX LSi..."PEARLY"
'92 White Pearl SVX LSL w/touring pkg..."SVXY"
'92 Teal SVX LSL w/touring pkg..."ALCYONE"
'96 Polo Green LSi ... "MIDORI"
'00 Black Dodge VIPER RT-10... "VINNIE"

Engineers do it with precision.
English teachers are novel lovers.

Home: larrysingeriii@comcast.net


SVX FEVER, CATCH IT AT A MEET NEAR YOU !!
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 09:32 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
© 2001-2015 SVX World Network
(208)-906-1122