Tires: ST tire mold, tire mold, aspect ratios

Question
Researching the Special Trailer tire has revealed on numerous occasions that many are built on old left over molds. If so where did they come from? Is there any adverse effects when using all new materials to build a new ST tire on an old mold? The old molds must be approved by the DOT so why even bring up the subject other than just to just bolster ones credibility?

Cal

Answer
Cal,

I bring the subject up because of the unusual sizing of ST tires.  The 75 and 85 series sizing is gradually being replaced with lower aspect ratios (and wider section widths).  Plus some ST tires use the old sizing system called AlphaNumeric - as in G78R15.

Plus, there is the credibility thing - and this sometimes adds to the validity of what I say.  

And I am about to add some more:

It isn't the molds that are approved by the DOT.  It is the tires that come out of the molds that are "approved".  Actually, the tires have to "comply" with the regulations.  NHTSA merely sets the rules, and then checks to see if the rules are followed.  They really don't approve anything except the regulations.