If you really want to see just how viable a tick can actually be, search "Tick Lives for 27 Years, 8 Without Food."
Not only did the female tick survive for 27 years, including the 8 without a host, once a host was re-introduced, she was able to lay eggs. Even though the last male tick died off years ago. She was able to store the sperm until conditions were optimal again.
I do not think ticks perish in the winter any more either. With or without a host, in NYS we have had several cold spells over the last few Winters, with day after day of negative numbers, and yet they still survive. I would bet that they can go into a catatonic state or cryptobiosis, like the tardigrade or water bears do.