To provide near-optimal error-correcting performance for multi-rate turbo codes and minimize the size of additional memory, a new decoding method is proposed in this paper. The proposed decoding is based on two methods: hybrid sliding window and dynamic metric encoding. The new window scheme combines dummy metric calculation and border metric storing methods to halve the border metric memory and improve the error-correcting performance for multi-rate codes. The dynamic encoding of metrics also significantly reduces the border metric memory without degrading the performance. Employing the two proposed methods reduces the conventional border metric memory by 83%. In addition, the superb error-correcting performance of the proposed method is verified for various code rates by conducting intensive simulations for 3GPP LTE codes.