Unsafe at any speed....

Olde Volks Place wrote:
CapriRacer, as a tire Expert could you tell us if tires are still made from REAL rubber today like they where years ago or are they mostly man made compounds like rubber.

if they are compounds do they have any real rubber in the mixture and if so what is the ratio of real rubber to man made ? like 10% real 90% MM

Thanks

I am assuming you mean natural rubber and synthetic rubber. Natural rubber is the kind they get from tapping trees. The problem here is contamination. If you think that tapping trees would result in bark, insects, leaves, and other foreign materials, you would be right. As a result they grade natural according to how it was processed and how much contaminants it has. But natural rubber is one kind of rubber - polyisoprene

Synthetic polyisoprene is made from petroleum. Chemically, it is identical to natural rubber, and it has no contaminants, making it a bit better suited for critical applications.

- BUT -

There are other types of rubber - styrene-butadiene, isobutylene, for example - and they have different properties than polyisoprene - some of those properties are quite useful in tires. So typically, tires use certain rubber blends in certain parts of the tire and other rubber blends in other parts to get the properties needed for the part of the tire they are being used. The desired properties are identified independent of the type of rubber, by a series of laboratory tests.

So natural rubber is not naturally superior to synthetic rubber. (Ha, ha, ha. I crack myself up!!) It has the benefit of being competitively priced with synthetic polyisoprene, so many tire manufacturers have mixing formulas that take advantage of the price difference between the two. So the ratio of natural to synthetic varies according to the price split.

Rubber chemists have done an excellent job of developing these mixing formulae, and the performance of tires does not follow the cost of natural rubber.

Recently, China has entered the market (actually many markets) in a big way and has been buying up the supplies of natural rubber - driving up the price. They have also been buying petrochemicals - driving those prices up as well. I don't know what the current price split is like, but because both commodities have been impacted this has had a huge impact on the manufacturing costs of tires - and those have been reflected in the price of tires.