  Let $tsp(G)$ denote the length of a shortest travelling salesman tour in a
graph $G$. We prove that for any $\varepsilon>0$, there exists a simple
$2$-connected planar cubic graph $G_1$ such that $tsp(G_1)\ge
(1.25-\varepsilon)\cdot|V(G_1)|$, a simple $2$-connected bipartite cubic graph
$G_2$ such that $tsp(G_2)\ge (1.2-\varepsilon)\cdot|V(G_2)|$, and a simple
$3$-connected cubic graph $G_3$ such that $tsp(G_3)\ge
(1.125-\varepsilon)\cdot|V(G_3)|$.
