Wheels are allowed as long as you meet the measurement criteria. At some airports they are very strict, others they don't bother to check but you can't guarantee this anywhere. Remember that cases may fit the measurements before you pack but they may expand when you have crammed everything in. I would recommend boarding as early as you can if you do have a wheely case as if you do board last there may be no room in the overhead lockers for your case and it will need to go in the hold.