Research investigating the interaction of polymeric materials (e.g. crumb rubber (CR) which is recycled tyre rubber) on the fatigue cracking and rutting resistance of asphaltic materials indigenous to Trinidad and Tobago is limited. Especially with regards to CR particle size, literature reveals no previous work done investigating its influence on Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB). This paper examines the effect of both concentration and particle size of added CR on the fatigue cracking and rutting resistance of TLA and TPB. The particle sizes ranges under study were ≤250 μm, >250 μm to 355 μm, >355 μm to 500 μm, and >500 μm to 710 μm. These particle sizes were added in concentrations ranging from 1% to 10% by weight CR. It was found that for TLA, the optimal CR particle size range and concentration to maximize rutting resistance were particles ≤250 μm at 5% CR concentration respectively. Pure TLA however showed superior fatigue cracking resistance compared to the CR added blends. For TPB, the optimal particle size and concentration for fatigue cracking and rutting resistance were >500 μm to 710 μm at 2% CR and 5% CR respectively. Adding CR to TLA and TPB can serve to enhance the life of the asphaltic materials. Utilizing CR can also offer great potential as a recycling option for the disposal of used car tyres in Trinidad and Tobago.