On 15 Jan, 04:54, DougC wrote:
On 12/30/2009 11:44 AM, Jobst Brandt wrote:

......
That carbon black in tires aids in wear resistance and wet traction is
well known and the reason why you don't see high performance auto
tires in any other color than black. *White knobby tires on children's
bicycles don't wear long or corner well anywhere, but they are a
standard of fashion for the little tykes.
......

No offense, but where does it say that carbon black aids in wet
traction? I haven't seen that mentioned anywhere so far.

Religious tenet introduced to 'explain' why patterned tread tyres grip
better in wet corners with smooth surfaces. Fillers had to be used
because raw latex was and is expensive, fillers also not only reduce
cost but stabilise the rubber product against stability problems due
to temperature fluctuations. With heat, the latex will crumb and not
provide the dry traction required, or economical wear rate.


The introduction of inert fillers was to stiffen the rubber and improve
its wear characteristics; the natural rubber also needed colorants in
order to try to help protect it from UV damage from sunlight. Carbon
black is one of a very-few fillers that can effectively do both jobs at
the same time--but then, iron oxide seemed to be another.

as does zinc oxide.


Iron oxide seems to boost traction more than carbon black does; why else
would Kool Stop be using iron oxide in their brake pads, and not carbon
black instead?

Because they want the blocks to crumb easily so as to provide steady
revenue from replacements.

Salmon Kool-Stops have a pretty good reputation far and
wide, yet we see no red-colored modern performance car tires. ?:|

?

Who wants to buy a car with four corners of rust?