Re: What are today's tires made from?????

Posted by Ken McWilliams on November 02, 2000 at 10:14:07 from (38.232.245.127):

In Reply to: What are today's tires made from????? posted by Alberta Mike on November 01, 2000 at 06:44:54:

Mike,

Tires are made from petroleum as others said. The most popular rubber starting material is butene (not to be confused with butane) which becomes butyl rubber. The molecular structure has bonding sites as a result of double bonded carbon atoms in the organic/carbon chain.

From a thermondynamics point of view the linkage between carbon atoms can be single bonded, double bonded or triple bonded. Single is: C-C-C-C, double is C=C=C=C and triple I can't show on this word processor. The triple bond has the highest energy per bond. Acetylene is triple bonded (used in a torch)and gives off great energy as you know in a torch. Double bonded carbons are more stable than triple, but lesser energy than triple bonded. All of matter wants to go to the least state of energy (entropy). When the butyl componds that have considerable double bonds is reacted with sulphur, the double bonds are broken and the sulphur becomes the link between smaller monomeric molecules of butyl. Thus, the vulcanization using sulphur breaks the double bonds and joins all together into large single bonded molecules known as rubber and is the lower engery form and very stable.

Carbon is used to add toughness and abrasion resistance. There are other materials added to the rubber to make it resistant to sunlight (UV blockers) and antioxidants to slow the aging in the atmosphere.

Butyl is the base rubber, but there are other rubbers used: isoprene, nitrile,and styrene butadiene (SBR) to mention three of them. Sometimes different rubber bases are co-reacted to achieve certain properties. Hose rubber often uses nitrile, standard o-rings use buna-n.

In the early days natural rubber was added to get the desired properties to synthetic rubber. Isoprene rubber is the closest synthetic chemically and physically to natural rubber.

The threads used in tires are for reinforcement. Nylon, rayon, polyester, and steel are used in varying degrees to accomplish the desired properties. Steel cord is used almost exclusively in the beads for good dimensional stability and fit to the wheels. Without the reinforcement cords, tires would be more like beach balls and would not keep shape very well.

The tread is primarly designed for traction and for operating on wet pavements. The cleats are obviously used for traction on terra surfaces. The primary use of tread on highway tires is to operate on wet pavements. The deep tread grooves running in the direction of rotation allow water to pass through. Without such, tires would hydoplane and be like driving on ice. Thus, bald tires are not safe on wet pavement. Drag slicks are soft and very sticky for traction on dry pavement, but treacherous on wet pavement (been there done that).

This is what little I know about tires, except they're expensive when I go to buy them.

Ken McWilliams
Dayton, OH

Follow Ups:

• Re: Re: What are today's tires made from????? josh wakeman 12:24:16 04/29/02 (0)

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