The use of Crumb Rubber Modifier (CRM) to improve binder performance has been successful in hot climates. On the other hand, field trials aiming for possible reduction in transverse thermal cracking using CRM, as a binder modifier, have been disappointing. Low temperature properties represent an area of interest. The production of CRM binders involves controlling both material and interaction condition variables to optimize binder properties. The Strategic Highway Research Program (SHRP) set requirements for binder specifications at low temperature measurements. These requirements are performance related. The use of SHRP fundamental properties to monitor the production of CRM binders allows optimization of the binder performance characteristics. In this paper, the effects of material variables on the low temperature properties of CRM binders are compared. The development of low temperature properties as interaction conditions change are presented. The possibility und the extent of regulating low temperature properties are discussed.