| Country: | IRL |
| Type: | R |
| Route: | 166 |
| Length Km: | 41.8 |
| Terminus A: | R246 Tallanstown |
| Junction: | N52 Gilbertstown M1 Junction 15 R132 Castlebellingham Crosses River Dee Passes through Annagassan R170 Murray's Cross Passes through Clogherhead R167 Termonfeckin R899 Drogheda (Newfoundwell Road) |
| Terminus B: | R132 Drogheda (Patrick Street) |
The R166 road is a regional road in Ireland, located in County Louth.[1] [2] [3]