StephenH

I'm working on an upcoming trip where it is known to be bumpy and full of goathead thorns. My wheels just happen to be tubeless-ready, although I've never tried tubeless tires. I think they say for up to 40mm tires, although the frame can likely handle a little larger. Is there a preferred less-flats tire in that range?

Spoonrobot 

Tires with tread or slick?

For treaded tires I love the Kenda Happy Medium SCT in 700x40. These are so good I don't plan to use any other tire for the foreseeable future. I race on them and have noticed they seem to roll 99% as fast as smooth tires when in mixed groups on pavement. Flat resistance is very good, bonus is that they are fairly easy to mount.

For slicks the Panaracer Gravel King Slick in 700x38 is wonderful. Rolls like tubular and is lightweight and true to size. A little difficult to mount the first time but easy the times after. Flat resistance also appears to be good IME.

FWIW I've heard Stan's Race sealant handles goatheads better than the regular Stan's but I don't have any direct experience.