No. Take a 2nd bag and spread the load.
And, AFAIK, the checked-in allowance is 20kg. We flew Ryanair on Friday and Sunday and, on the return flight, each bag was between 15 & 20 kg and we weren't charged excess. We did pay, at time of booking, the €3.50 baggage charge.
From my booking confirmation e-mail of 21 April 2006 ..
"*******************************************************************************
BAGGAGE ALLOWANCE POLICY FOR ALL NEW FLIGHTS BOOKED FROM THE 16TH
MARCH 2006 ONWARDS
*******************************************************************************
The checked baggage allowance is 20kg per person (no infant allowance)
No pooling/sharing of baggage allowances is permitted, even when
passengers are travelling together on the same reservation."
Our flight was to/from UK.