Product review (5 stars): Exact OEM replacement and works great
This is the OEM Whirlpool part, the same one the factory repair guys use.  I installed these about a month ago as the originals had hardened and developed flat spots that made a loud thumping sound.  Problem solved!  Dryer runs nice and quiet again.  When you remove the old tires, make sure to clean out all the dirt, hair and lint from the shafts.  I used alcohol to further degrease and clean the shafts before applying a light coat of lithium grease.  When you put the new tires on the shaft, make sure they are turning freely.  If they don't, take them off and find out why.  They have to turn freely or they will burn out fast.