What kind of license is needed to operate tow truck in Texas?

It's in accordance with Gross Vehicle Weight Rating. Under 26,001 GVWR, just a standard drivers license. 26,001+ GVWR requires a Class B CDL. Gross Combined Weight of 26,001 lbs. or more and towing a vehicle with a GVWR of 10,001 lbs. or more requires a Class A CDL.