Flatout and Tireseal are both good. I'd have to go out to the barn to see which one I used on one tractor. Also tubes. I have had 14 in tubeless snow tires on the front of my
L2250 with tubes in them. The tire shop doesn't recommend it. I remind them my top speed is 12 mph and that I haven't had a problem in over 20 years. Finding a rim for that tractor isn't easy.
I see that you got it fixed, but if you have trouble again -- here's my "fix" from now on as I've "tried" just about all of them with little or no success.
I too had a slow leaking front tire on my Kubota
B20 and had tried several different brands {including a tire shop!} as well as removing the tire, wire brush on drill the wheel, prime/paint, clean bead on tire, apply black liquid rubber around bead and remount -- STILL went down over time! as I don't use the tractor regularly.
SOOO -- I got creative -- circular saw/cut up enough scrap wood to make enough "dust" to almost fill one of those 1 gallon ice cream jugs {the square ones}/added anti-freeze to make it liquid {not too runny, just enough

} then broke down the tire AGAIN and added what I thought would do the trick.
I have not added air to that tire since -- I wish I had written the date down somewhere -- over two years ago at least.
Talk about cheap -- and it won't rust the rim like "Green Slim" will!
I have now made another "batch" as I have used this stuff {Johnny's MIRACLE tire sealant/final!

} and have a couple of friends who "borrow" some which depletes my stash.
"Patent Pending"?

Final comment -- this works in 4-wheelers, SXS's etc. but NOT automotive as it would probably vibrate at higher speeds although in my Yamaha Rhino 660 {top speed is 38 mph} I haven't noticed any.