The REI-brand rubber tips (REI Trek Pole Walk Tips) work great on my TI Goat poles. They are smaller and much lighter than the Leki-brand rubber tips, and so do not affect the weight or swing at all. To put them on, first drop the REI rubber tips into boiling water for a minute or two to get them to stretch better. Then take the hot rubber tips out of the water, place them on a counter or work surface, and push the TI Goat pole tip down onto it. Even hot it will take some force to get it all the way on, but once the tip is on and cooled, its not going anywhere.
Mine are into their second hiking season and are holding up great.