Is Zakat obligatory on two dump trucks leased to a company, knowing that their value is one hundred and forty thousand Riyals, and they generate a monthly income of six thousand Riyals?

There is no zakat on the two trucks designated for hire, nor on their value. Zakat is only due on the income derived from their rental, if a year has passed over it and it has reached the nisab either by itself or by combining with other money or trade goods. The amount of zakat is a quarter of a tenth (2.5%).