Iowa Public Radio: Towable RVs now account for well more than half of the revenue at Forest City-based Winnebago Industries. Second-quarter profits and revenue are up substantially for the recreational vehicle manufacturer from a year ago. The quarter that ended Feb. 24 was the first full quarter since Winnebago bought Indiana-based towable RV-maker Grand Design. The results show revenue up more than 26 percent from second quarter 2017 and an increase in profits of more than 37 percent.