Pilot reported fumes in the cockpit after switching fuel tanks during flight. The pilot diverted to make a precautionary landing.

Narrative

I was starting my descent into ZZZ from ZZZ1. I was picking up my plane Aircraft X; from the annual inspection. I was 3 miles east from ZZZ2 and directly overhead of the raceway. I swapped fuel tanks and I could smell a distinct smell of oil/rubber burning. I immediately swapped the fuel tanks back and [requested priority handling] with ZZZ3 Approach. I was already talking to them for flight following. At that point I requested vectors to ZZZ2 gave fuel quantity and souls on board. At that point the smell continued; however there was no sign of smoke or fire. I decided to get the fire extinguish ready and available if a fire broke out. By the time I retrieved the fire extinguisher I was already passed the ZZZ2 airport and could visibly see helicopter traffic over the runway. At this point the burning smell was gone and there was still no sign of smoke or fire. I requested to proceed to ZZZ3 which Approach asked if I would like to proceed to ZZZ. At that point I determined the smell was gone and I was maintaining altitude and airspeed; so I proceeded to ZZZ. Once Approach handed me to ZZZ I told them I did not have the burning smell and would switch fuel tanks 1-2 miles from the runway. I swapped fuel tanks and had no smell. I then landed without incident. Once I landed I visually inspected the engine and cockpit and there was no sign of fire damage or short circuit. During the flight I did have all available vents open and I believe this smell was from the ground.