While there's no standard semi truck mattress size, the majority are around 80 inches long and 40 inches wide.
What size mattress is 38x80?
Twin XL Mattress
What size is the tractor bed?
Although most mattresses for semi-truck sleeper bunks measure around 80-inches long and 40-inches wide, there are a large number of semi-truck models with different mattress specifications which makes buying the correct mattress size surprisingly complicated.
What size mattress fits in a semi-truck?
42×80 inches
What size mattress is in a Kenworth w900?
Included in the 72-inch model are a full-length clothes closet, storage shelves, insulated rubber floor mats, vented access doors and 42-inch mattress.