What brand? What model? How do you like them? What do you know about the studs? Other studded tires you have used? How much use do they have on them?
A long time ago I had some IRC Blizzards. They had I think 112 (about) long steel studs. The studs wore out quickly. I replaced the studs with some new Nokian studs, but the nest in the tire was made for a longer stud. It did not work as well as they did when new. I gave them away.
At least 10 years ago I bought some Nokian Extreme 296's (294?). I try and save studded tires for only ice and snow. I have another mtb with knobbies for dry roads and fresh snow. I use the Nokians every winter. There is not typically lots of snow and ice here. I don't know how many miles are on them. They grab great on ice, bumpy ice with footprints, and hard packed snow on the road. I took out 10 studs and measured them, compared used to new unused studs after a few years. The studs don't get shorter (tungsten carbide) but, the casing of the tire gets soft, and they sink into the tire over time, giving the effect of shorter studs. What does happen, is that the sharp corner of the shape of a cylinder end, gets rounded over a little. They still are OK, but not as good as new.
Last fall I upgraded to Schwalbe "Ice Spiker Pro" tires. Almost 400 studs, thinner more flexible side
walls and lighter, wider than the Nokians with pointed carbide studs. They grab great, but I just realized the sharp point will round over and wear faster than a cylinder shape. And, it's happening already. Huge fail. !