Among the various techniques to improve performance of Turbo Codes (TCs), it was shown that the prefixing of a rate-1 accumulator to a turbo encoder can represent a suitable solution that does not alter its coding rate. In this paper, we study the application of this precoding technique to improve the performance of TCs in the context of the Long Term Evolution (LTE) standard. To efficiently select the best precoder parameters in terms of convergence, we propose a design tool based on the real exchange of extrinsic information between the constituent SISO decoders. We also introduce two new precoding structures and we present design criteria leading to good interleavers for Precoded TCs (PTCs). Significant asymptotic performance improvements can be achieved with the proposed schemes.