Deni the goal is to have - at least - 3 teeth cutting at the narrowest point; so a 065 tubing needs a .022 tooth spacing or an amazing 45 tpi. If you have less than 2 teeth (even 1.9) you can expect to tear teeth off, even on the very best blades.
To cut .065 wall tubing, the coarsest blade would have at least .033 spacing or 32TPI which is available from some sources. I'd use more than 40 TPI if I could find it.
Even a 100" carbon blade should last for at least 100 square inches of cross section in mild steel before getting dull (notice I didn't say 'losing teeth'). Bimetal blades should last 5X as long. If you loose teeth and the remainder are sharp, then your saw is cutting with too much down pressure or you are using it for too thin material. (there are other causes, but these are the most common).
I hope this helps save you money on good blades.