A C172 Pilot executed a go-around following two encounters with the probable wake vortices from a preceding landing aircraft.

Narrative

I was in the pattern to do some touch and goes after returning to the area in a rented C-172. There was another C-172 ahead of me with a student and an instructor flying patterns. The other plane made a very long downwind. I called to him asking his intentions. He replied he was about to turn base. I then extended my downwind to accommodate his long downwind leg. I subsequently turned base when I thought it appropriate; given his position on final. I believed I was allowing a reasonable distance behind him when I followed him into final. He then landed and I was near the threshold and about 75 feet AGL when suddenly my plane moved over to the right about 50/75 feet. I corrected and continued my approach. Soon after I was back on the centerline and still descending when I found my plane off to the left side of the runway. I then aborted my approach and went around the pattern. At that time I realized that I had likely encountered his [wing tip] vortices; first one side; then the other. I was surprised because I always allow extra distance for larger aircraft ahead of me but; in this case; both planes were of similar size. I will always allow more distance when following another aircraft in the future. Even though he was clear of the runway before I would have landed; I still encountered his wing vortices.