Too tips...if you are planning to drive from Dublin Airport keep in mind these...
1.The M50 Dublin ring road gets extremely busy and slow moving to the north and west
2. The road which joins the M50 to the M7 and M8 is not a motorway. By the town of NAAS there are widening works ongoing( since years) which make this section truly horrible. AVOID AT ALL COSTS
3,Consider leaving the M50 to join the M6 in the direction of Galway making that part of your itinerary
4. Several car rental companies have contracts to pay the M50 tolls electronically and recharge the customer.All other tolls MUST be paid in cash at the respective toll plaza...keep coins handy.
FINALLY...to avoid the tourist buses clogging up the Ring of Kerry consider doing the Ring of Beara instead.even more spectacular and the roads are too narrow for the full size buses/ coaches