The rest of heat modeling got turned on last night, although it is not completely hooked up yet, and what is hooked up is only in the Dirt B tire. It is completely not calibrated at all, so it is not really even suitable for a taste. All it is good for at the moment is to make sure it is hooked up: that behavior changes, that the HUD shows changing temps, etc.
The gist of the model is that the road flashes temperature into the contact patch (flash heating). That heat diffuses into the bulk rubber of the tread. The tread heat transfers with the ambient air and the carcass. The carcass interacts with the internal air. The internal air interacts with the rim. The rim interacts with the well air (air 'inside' the rim well). The rim air interacts with both the ambient air and the brakes. There is also evaporation cooling in the wet.
Depending on the resolution of the contact patch and the tread, each of those has many "heat reservoirs", one per seta in the patch and one per tread element in the whole tread. Right now most tires have 36 of each. Beyond that there is also one reservoir for each of: internal tire air, rim, well air, and carcass. FlexiCarcass may have more than one. ElementCarcass will have more than one. From the tire model point of view, the road temp, ambient temp, and brake temp are just numbers fed to the model each time step.
Bottom line, most current tires will have 76 reservoirs.