There is no correlation between rear tire heat and brake drag. The brake disc and caliper assembly would have more heat when the brake drags, not the tire. Engine thrust overcomes any incidental brake drag present and the tire just applies the force necessary to move the bike forward.
I tend to agree.
The more resistance there is to the motorcycle moving forward, regardless of the source of that resistance, the more engine power there is required to move the motorcycle forward. That increased power is translated in to forward motion by applying more force to get, and maintain, the rear wheel turning. In the case of a dragging rear brake, the required additional force is being applied to the mechanism that turns the rear wheel, not where the tire is in contact with the road. Because of that, I would think that increased final drive temperatures would be a far better indicator of a dragging brake than tire temperatures.
The question is, how much brake drag is required before that temperature increase can be measured with the rudimentary tools that most of us would be using to measure it? I suspect that most of us would notice a rear brake problem from other symptoms long before we would notice an increase in final drive temperature and make the connection between that and a dragging rear brake, most notably the increased temperature of the rear brake rotor due to the brakes not releasing.
