TCP, the transport protocol used to carry the major portion of the internet traffic, performs poorly in Mobile Ad Hoc Networks (MANETs) as broadly reported in the literature. This is mainly due to the interactions between TCP and lower layers protocols. Among these, routing protocols have perhaps the greatest impact on the performance of TCP. In this paper, by extensive simulation, we evaluate how TCP interacts with some of the IETF standardised reactive (AODV, DSR) and proactive (OLSR) routing protocols under varying network conditions such as load, size and mobility. In contrast to most of previously reported studies, which have relied solely on TCP traffic, we consider a more realistic traffic carrying a mixture of Constant Bit Rate (CBR)and TCP. We also show how appropriate tuning of route expiry parameters in reactive protocols can improves TCP performance considerably while still generating less routing overhead.