Massami can do it with his left foot while winning a heat in another class. Blindfolded no less.

I agree that it PROBABLY doesn't matter which end. I WOULD say, however, that to do it at the rear requires your rear pod to be PERFECTLY balanced side-to-side, and that balance will change depending on motor used, etc.

In fact, now I'm curious. There is FAR more wire (winds) in a motor now with brushless than there ever was in a brushed motor since those winds now fill the can and the magnet spins. How much weight difference is there between, say, a 17.5 and a 10.5?. Whatever difference would be CLOSE to being centered, but I can't believe it would be exactly, at least not to within the gram or so I tweak the front of my car to prior to heats.

When I build my cars I don't even weigh the rear pod for balance--as far as I'm concerned the tires contact patches are immoveable relative to each other, as long as things are pretty close (to keep tire wear even-ish) then it's close enough. So for me

I always do the front wheels which is how I learned.

I saw Mike Blackstock set tweak on his car--two coins on the front tires. If it's good enough for Mikey...

I HATED the Hudy tweak stand that came in the "All-in-One" set. Tried it a couple times, wasn't for me. That said, I'm sure there are folks who can make 'em sing...just nobody I've ever met.

I actually use four small scales to set balance or tweak my cars. On the 1/12 car I don't even turn the scales under the rear tires on.