I turned my 20+ year old MTB into a singlespeed, using the original 26” wheels, v-brakes, and updating to tubeless tires. The tires are Panaracer Fire XC Pro 26 x 2.1. It is my understanding that these tires are discontinued, but they are still available, and there are others out there. I learned from a couple of YouTube videos how to properly tape and seal the rims for tubeless use, and it has worked great for me.