Not a grip issue as I hold the bars rather lightly using a paddle gadget on the throttle and a Kaoko throttle lock. Left mirror blurry, right mirror clear. Finger tips on left grip or clutch lever VERY buzzy. Finger tips on right grip anywhere, smooth no buzz. I also have bar end weights. I'm not expecting a Valkyrie (nickle trick) but I think the vibes would be even.... This is a new phenomenon, I've had the V since last July.
Idiot stuff that I've used in past lives to cut down vibration:
a) reposition the switch clusters (i.e. change the angle of the switch clusters up or down vertically) to change the frequency of the vibration. You're seeing the end result of of sympathetic vibrations traveling up to the handlebars.
b) if there are bar weights on the bars, change the weights for heavier or lighter ones to change the frequency of the vibration. Remove the weights from the left, the right, and both to see if anything changes.
c) move the handlebars vertically up or down in the handlebar holder (guess why?)
d) visit a KLR or mo'sickle web site and look for mirror vibration isolators. This has the added benefit of moving your mirrors up and out slightly for better vision so you can see the texting soccer mom in her Suburban bearing down on you.
e) trash the mirrors and try another pair which may have different sympathetic vibration characteristics.
f) check your motor mounts for correct torque.
g) check your steering head nut for proper torque.
h) you already mentioned your tires are tired, and probably out of balance as well. not a large chance, but since you're eliminating vibration sources...
i) check to see if the left mirror is broken or loose in the mirror housing. Sometimes (rarely) they'll break internally.)
j) sell the mo'sickle and take up Corgi raising.