Tires contain a percentage of a UV anti-oxidant wax-IE with driving and the heat generated by driving, the important
blooming" process takes place to replace the wax that has gotten to the surface and is used up by exposure is replaced The blooming pushes the surface was with a "dressing" away, combine that with the evaporation of either the dimethal silicone or PDMS leaves the sidewall. Over the years have experimented with various resins to overcome this action. Lately, after some thinking, applied two coats of common liquid acrylic floor wax and allowed it to dry. The floor wax does not create a gloss, more of satin finish. At that point, I applied a common PDMS water borne dressing over it. The acrylic wax provided sort of a barrier over the UV wax and appears to have extended the life of the PDMS dressing. Will play with it more come warmer weather.