either way, you want to use the same material on both front and rear for the best results. Foam will tend to provide better traction, however it will also tend to wear significantly faster and be more expensive to maintain, plus as foam tires wear, they shrink in diameter which will require you to change gearing as your FDR rollout changes. For general bashing I would invest in a set of quality rubber tires and from the looks of things in your avatar, if you're running an SCT, then I would consider installing 17mm hex adapters and going with a set of GT8 wheels... for really good performance and long tire life, I would recommend a set of Sweep Belted Radial EXP50