Relevance. Rating Newest Oldest. Best Answer: A 14' truck is right for the dimensions, but you might be able to get it to fit into a 10' truck with a little coercion. A king size bed is 6'x6' 8 and the opening of the 10' uhaul is 5' 11 x 5' 6 The 14' truck opening is 7' 1 x 6'1.Bending a mattress with springs can cause damage to it.Source(s): Uhaul.com and the Wikipedia entry for beds. Chris C · 7 years ago.elevance. Rating Newest Oldest. Best Answer: A 14' truck is right for the dimensions, but you might be able to get it to fit into a 10' truck with a little coercion. A king size bed is 6'x6' 8 and the opening of the 10' uhaul is 5' 11 x 5' 6 The 14' truck opening is 7' 1 x 6'1.