DES MOINES — State revenue predictors Friday boosted Iowa’s tax collections forecasts by $240 million over the next 16 months mostly due to the positive effects of federal tax cuts, but that short-term boost likely won’t erase the need for making spending cuts in the fiscal year that ends June 30.The three-member Revenue Estimating Conference bumped up the current-year growth estimate it made in December by $33.3 million, to a total of nearly $7.271 billion.