Tds from payment to transporter

As i understand, non-deduction of tax is applicable for the benefit of small transport operators provided they OWN less than 10 vehicles and give a declaration to that effect. Since you say that they operate hired trucks also (in which case they r not the owners), I would think that such transactions are not covered under exemption and TDS is applicable.

In his regard, how company knows wheter transporter is owner of vehicle or not

I said so in this case bcoz u said outside vehicles are hired. if u do not know that such vehicles are hired and if u act in good faith provided u have received the declaration & PAN from the transporter, u r not at default if u dont deduct TDS, i think.