CHICAGO, July 16 (Reuters) - The U.S. Treasury Department on Friday asked its primary bond dealers for their outlook on issuance sizes across the yield curve and when reductions should be considered by the government. The dealer questionnaire, released on Friday, starts the process for the Treasury’s next quarterly debt refunding announcement in August. Dealers were also asked for their expectations for the sizes of Treasury Inflation-Protected Securities (TIPS) auctions during the remainder of 2021 and for 2022, as well as their views on the main drivers of TIPS yields. “To what extent have these movements been driven by TIPS liquidity, inflation expectations, or other factors, and what indicators do you use to inform your understanding of how TIPS are performing across the curve?” the questionnaire asked. (Reporting by Karen Pierog; Editing by Chris Reese)