Looks like it is time for a front tire for the old F800.
Size is 90/90-21 MC 54 H
I think the first tire was a Bridgestone Battlax. The current front tire is a Metzler Tourance which was a pretty fair match at the time it was changed.
Nothing against either of these tires as they have worked well- just getting a bit thin and I think it's what I detect in the handling change.
The rear tire that I changed is now a Heidenau K-60 which has been great, has been wearing like iron, but seriously tough to mount- on my hands and knees. Looks like Heidenau is now offering a tire sized for the front.
Mostly the pothole laden roads here in the Northeast.
TIA
OM