You could eyeball it if you have a ruler that has 64th's or wrap a piece of tape around it then take it off and measure it. Use 1/2 the tape measurement (circumference) to get the diameter. Tip-top tubes are in 64ths of an inch
ok thanks guys, the reason i ask is that the rod is to long to carry in my truck (camper cover on it) and i was just going to replace the tip and give it to my next door neighbor as he loves to fish when he can.