My family booked a private driving tour for Ring of Kerry. The price is 420 Euros and the website states tips are not included. What is a standard amount of gratuity for a private tour?
Tips, by their nature, could never be included. Sounds like the tour company is fishing for extra money from north american tourists! If the guide does a fantastic job and deserves a tip, perhaps you could give them €10 or maybe even €20 at the end of the trip.
We did a semi- private tour on Inishmore last year (shared with another couple we met after arriving) and tipped the driver/guide €40. The tour itself was €20 per person, so we effectively doubled his take on the tour, and the other couple gave him an extra €30. But he really went out of his way, and made for an exceptional time, and it amounted to less than $25 extra per person for a whole day.
Not knowing how many are in your family, but just a guess is that at least €40 (roughly 10%) would be a good starting point for all of you, assuming the tour is good, more if you feel like it’s appropriate. Have a great Ring Tour!