Hi Neil, I've been with Sierra 3 timesand I think you'll love the setup and rides there. Tyre choice depends on how you agressively you ride and whether you are "light" on the bike.

The terrain is predominantly dry and dusty with a liberal scattering of rocks, many of which seem a bit more "pointy" than the rocks over here! There are also a fair number of thorny bushes.

Tubeless downhill tyres will give you the best chance of a puncture free holiday, the downside is they're expensive and heavy. This what the guides use, but they ride 6 days a week for 11 months of the year!

I ride pretty hard and fast and have rented both hardtails and full sussers and only had two pinch flats and one thorn puncture in 3 weeks.

My partner has had one pinch flat in two weeks riding, and she rides lightweight 2.1 Continental Speed Kings on a full susser.

For info the rental bikes have 2.3/2.4 Hutchinson tubed tyres with a block tread pattern, they work well in the dusty conditions and the bigger profile helps reduce pinch flats over the rocks.

My recommendation would be a 2.3+ tyre with heavy a block pattern, tubeless if you have the rims and can afford it, if not run a higher pressure than over here and take a few tubes. Changing a tube in the shade under a tree when it's 28 degrees in the sun isn't really a hardship. Enjoy, and give my regards to Alan, Mary, Dave and especially Jonny, THE best guide I've had the pleasure to ride with. Kev