In our paper "A new benchmark set for Traveling salesman problem and Hamiltonian cycle problem", we described a new benchmark set for the Traveling salesman problem based on difficult instances of the Hamiltonian cycle problem. Hence, the 45 instances contained within can be viewed as both instances of TSP, and of HCP.
The 45 instances are available for download from the link below. The instances are in HCP format. All instances are known to be Hamiltonian.
TSP and HCP Benchmark Set (266KB)
If you use the TSP/HCP Benchmark set in your research, we request that you kindly cite our paper as follows:
Baniasadi, P., Ejov, V., Haythorpe, M. and Rossomakhine, S. "A new benchmark set for Traveling salesman problem and Hamiltonian cycle problem". Computers and Operations Research, submitted 2018. Available at https://arxiv.org/abs/1806.09285