Scott, there are two issues to be addressed with new tires.
One is putting them through an initial heat cycle to condition the
rubber. If done right, it is supposed to improve durability and may
even reduce the "bad" effects of later heat cycles.
The other is getting rid of the mold release compound, which is a
layer of slippery goo at the surface of the tire. This is generally
done by "scuffing in" the tires by driving on them. Aggressive
driving takes care of it faster. Heat cycling done on a machine is
unlikely to have much effect on the mold release goo.
I think you're combining the two effects because some people heat
cycle the tires by driving on them, sometimes aggressively, and that
takes care of scuffing up the surface at the same time.
According to the folks who seem to know the most about tires, here's
what the heat cycling process is intended to do: When a tire is first
made, the rubber polymers are in long linear chains. Heat cycling ie
meant to break those chains into shorter ones while the tire is warm
enough for new links to form. Those new links connect adjacent
chains, creating a web that is stronger than the linear chains by
themselves. The term that's often used is "cross-linking". To
accomplish this, the tire should be heated up to a high temperature,
and rolled under a load to "knead" the rubber. That can be done
either on a machine or by driving on the highway (I wasn't able to get
mine up to the recommended temperature driving on the highway on a
fall evening though). Aggressive use, while it will heat up the tire
faster, will probably just tear up the rubber and won't result in a
good heat cycle. Otherwise, we wouldn't have to heat cycle the
tires...we could just start using them, and the first autocross would
be the heat cycle. The final step is the let the tires cool evenly
with no load on them for 24-48 hours to let the cross-linked bonds
form. Leaving them on the car on the ground creates cold spots on the
tires that will cool too quickly to let the bonds form.
That's how the theory goes, anyway. I don't really know if heat
cycling does any good. When I got the old Kumho ECSTA V700s (the ones
with the Victoracer rubber compound), I didn't heat cycle them and
they got hard before the rubber wore down to the cord. When I got
Hoosiers, I had them heat cycled because with tires that expensive it
wasn't much added expense for the possibility of prolonging their
useful life.
I don't know if the Toyos need to be heat cycled, but Toyo does
recommend shaving for use on dry pavement. They may not only have a
lot of mold release compound (if that's true), but they come with very
deep tread for a race tire. Deep tread can cause a squirmy feeling as
well.
--
john@idsfa.net John Stimson
http://www.idsfa.net/~john/ HMC Physics '94
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