Dave's Cybertron Nattering:

     Tachymers

     The residents of the Speed Planet are obsessed with racing, and optimize
themselves for it.  One of the modifications they have made is the
installation of tires made from a weird glowing clear material.  As of this
writing (July 2, 2005), there's no official name for that material, but
there's been some discussion on various boards (including the AllSpark) about
what it is.  The following explanation expands on my comments in the AllSpark
thread.

     Tachymers are a class of polymer (long-chain organic molecules) that
react to Energon in useful ways, changing either their surface or bulk
properties with the application of Energon of various frequencies and
amounts.  Discovered by scientists on the Speed Planet centuries ago, they
have been constantly refined by the Speedians since then.

     Tachymers come in two basic varieties: Glass (amorphous) and Crystal.
Glass Tachymers are most commonly used in tires, while Crystal Tachymers are
used in structural designs (especially in Speed's rare flying Transformers).

     Glass Tachymers are not brittle like silicon glass.  Rather, the term is
applied to both their clarity (light penetrates them with a 75% transmission
coefficient) and their non-crystalline structure.  When not energized, most
Glass Tachymers are flexible, and behave much like vulcanized rubber,
although they retain their flexibility over a wider range of environmental
conditions than rubber does.

     When energized, Glass Tachymers become up to three times as durable, and
their surface properties can be altered over a narrow range.  At one end,
tires made of this material act as racing slicks, and at the other end, like
off-road tires.  There do exist Glass Tachymers flexible enough to be shaped
into radically different shapes when infused with Energon, but as these
varieties are easily damaged and make for poor tires, little work has been
done developing them.  As a result, a typical Speedian's tires can adapt to
any road conditions, but remain tire-shaped no matter what energy patterns
are applied.  Also, to optimize for a specific environment, a Speedian may
sacrifice energy efficiency in another environment.  For instance, Dirt Boss
can still attain racing slick performance, it costs him much more energy than
it does Hot Shot (who himself has to spend more energy to go off-road than
Dirt Boss does). 

     Crystal Tachymers differ from Glass Tachymers in that they have a rigid
molecular structure.  Their surface properties can still be modified
slightly, but it is rarely energy-efficient to do so (i.e. reducing friction
on wings costs more energy than is saved by the reduction in drag).  The
primary use of energy-shaping on Crystal Tachymers is in altering the bulk
properties.  This material can be made as rigid as the strongest metal
alloys, or as flexible as composite fiberglass.  As a result, it is favored
by aerial Speedians, who can adjust their flight characteristics more easily
than they could with metal or ceramic construction.  It also allows for
desperation defense, by pouring all of one's reserves into increasing the
strength of the Tachymer.  

     Some Transformers from other planets have installed Tachymer material in
themselves, but the energy cost of using it has made it slow to catch on.
Many prefer traditional armor or tire material, as it costs no energy to
maintain at peak performance.

     (Later note: the first ep *aired* of Cybertron didn't have anything to
say on the matter, but does name the Speed Planet as "Velocitron".  There is
no hint of this name on the poster that comes with the toys, and "Speed
Planet" is capitalized as a proper name.)