Good on ya, Sakurama for using the ProSeal. That is by far the best sealant for this job and exactly what I plan to use when I do mine. I have a 1966 Mooney airplane with wet wing tanks sealed with that stuff, and they're still holding after 44 years. I recently installed new windows in the plane which are also sealed with that, and I had a bitch of a time removing the old sealant. It was still pliable and sticky.
ProSeal is available in smaller quantities than what Aircraft Spruce sells, for about $25 per tube. I used one tube to seal 4 windows, roughly 30 linear feet per bead, so one tube should easily do both wheels if you just seal around the nipples rather than try to fill the entire valley. The tubes are designed to be used with a pneumatic sealant gun, but I was able to just use a socket extension like a syringe plunger and it worked fine.
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2008 KTM 990 Adventure - SOLD