In high speed sweepers at approaching 70 MPH, I start getting front end oscillations. I Think I am feeling the rear work up & down a bit, but I am not sure which comes first & I have tried to figure it out, but, just can't. I had it on the tightest rear shock setting, tried the softest, sure didnt help. Its set in the middle now.
I have a Dunlop on the rear & Maxiss on front. Looking at the Maxiss closely, I am seeing something that might be a clue. The front edge of each block of rubber behind the grooves that drop from center toward the edge are raised from the rear edge of the leading block. When the stock tire started cupping the handling in sweepers got worse & worse, like riding a drunk cow.
What front tire are others running that dont cup up so fast? This one only has a few thousand miles on it. The tread wear is not even close to 'Worn Out". Maybe its Mill,, err, Metzler time?

Im not finding a Continental 100/90-19 available.

I'm starting to get a little cupping on the stock IRC front tire, noticed the cupping at about 5,000 miles and have been keeping an eye on it ever since. I was planning to replace the front when I replaced the rear but I'm just too cheap to toss good rubber. It hasn't gotten any worse after 8,000 miles so I'm just going to plan on a replacement when the front wears out. I haven't noticed any wobble at speed even with the cupping. Ever since I installed a fork brace the high speed wobble or wander went away. I'm running the rear shocks at thier second stiffest setting, anything softer and the bike feels mushy, anything harder and the butt gets sore.

It handled better before the front started wearing. What made me look at it was it handled so badly with the IRC's on when the front started wearing & got worse & worse as the tire wore. It cupped badly. After the fork brace went on the front tires stopped wearing so badly so quickly.( My opinion, may be a dose of wishful thinking)