Rolling Tires U$.$S$.$A$.$ sells premium off$-$road tires made by a variety of tire manufacturers to discriminating consumers. Currently, national demand is $250,000$ units per a $250$ working day year. As before, holding costs are $$0\mathrm{.}05$ per tire per year, and it still costs $$35$ to order and inspect each batch of tires. However, they have decided to institute a backordering policy. The backordering cost per tire per year is $$0\mathrm{.}15.$