Originally Posted by NiMo

FW05RR has a different top deck to stiffen up the fron end to make it better for Foam tyres, but is more of a pain to work on as you have to dismantle the front diff housing to remove the top deck.
I would personaly go for the older Rubber based FW05R spec and then upgrade the rear hubs/upper arms to the V1RRR if you prefer Foam