If they are baby back ribs the 3-2-1 method is a tad bit to long for them. The 3-2-1 was designed for spare/st louis cut ribs @ 225. However like HeSmellsLikeSmoke said, make sure your grate temperature is truely 225 using a calibrated therometer.
On a side note, I don't cook by time but I cook by look and feel and use temperatures/times as loose guidelines. If you want to wrap your ribs, cook the ribs until they are the color you want in them. Then wrap for 1 hr and check for doneness. If they somewhat tender but not quite bend test ready, sauce and put back on till the ribs pass the bend test or bone twist test.
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