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I run tubes in mine, for the stiffer side wall, and not having to worry about leaking air



The downsides are that you have to screw the rim or you could pull the valve out if the bead slips-this has caused some serious issues over the years, the extra weight costs some ET and the tubes will not allow the tire to lay perfectly flat. If you are bracket racing the last 3 hundredths don't really matter so extra tire life may be a reason to use them. Don't forget that good tubes cost over a hundred bucks apiece.