Thanks. And I forgot to mention that I'm not getting any bubbles from the tubes in water.
Yeah it's a "Comet 26". Has to be late 60's. The original V60 Tecumseh got replaced with another from a 71 Ariens. The thing that sucked was that I got rid of the first one prior to seeing that the Ariens had a different size PTO that I ended up using a sleeve on to get it to work. Rig job but it's been ok so far for a few years. I'm going to run that mower to the bitter end. haha.
Yea, that's it a comet 26. It came with a locked up 5hp briggs. I put a 9hp briggs on it, a lil clearance issue on the head side, nothing a angle grinder couldnt fix. With the gear ratio, pulley sizes, and only a 26"cut that 9hp turned it into a lil bush hog.
I built my youngest son a old snapper, not as old as the Comet, I say late 80's early 90's. It don't have the spring under the seat, has plastic handle bars, and gas tank is mounted right behind the seat. It came with 8hp briggs w/ 30" cut. I put a electric start 13hp briggs on it. It's a really good lil mower. It leaves a very nice, dam near perfect cut.
The pluses of going tubeless has to do with repairing a flat. If your machine is prone to punctures plugging a tire is easier and faster than a dismount/patch. The tires have to say tubeless on them or the liners will weep air. Of course the rims have to be up to the task also. I would also recommend bead sealer as that is where most slow leaks occur.
Clean up the bead area super good or any pitting in the area will be a leaking problem.
In fact a complete refurbishment in that area of the rim on the inside (cleaning, de-rusting, repainting, smoothing) is probably called for. I've even seen people either use several layers of paint or body filler (Bondo) to fill in the pits then sand it smooth. Then again this isn't the Concours at Pebble Beach and routinely airing up the tires may be just part of your normal routine and something easily dealt with.
You can leave the exterior of the wheel untouched for that patina'ed, old-but-still-good look.