When I drove around in my stupidly overpowered Clio V6 I made an observation. Even though the car is rwd, when doing donuts the front tire overheat almost as quickly as the rear ones. This leads me to the theory that the temps for the front tires are just approximations of the rear ones. Maybe the whole tire temp system is bogus?
Did anyone make similar observations?
It does look a little fishy. But just to play devil’s advocate, the front tires are always significantly cooler than the rears (peaking @ around 130 vs 190ish), and as the car spins, they are basically being rubbed sideways over the ground, so they should heat up at least somewhat.
I’m not at my XBox to try this at the moment, but what if you place the car against a barrier to stop it from moving, and then do a burnout to overheat the rear tires? If the fronts still heat up when they’re not moving at all, then I’d say you’re definitely on to something. But if they stay cool, then it might still be debatable how accurate the tire temperature modeling is, but at least we’d know it’s not just pulling numbers out of thin air.
what simulation mode are you in? Might make a difference
I just tried doing burnouts with the car’s nose against a wall, and only the rear tires changed in temperature. So that rules out the front temperature being linked to the rear, or being generated by some means other than the physics simulation. It does still seem like the OP’s front tires were warmer than I would’ve thought. I could be wrong though; it’s not like I’ve ever mounted an IR thermometer on a car’s tires while doing donuts IRL. 
Now, the much stranger thing that I inadvertently discovered was that in some places, like the runoff area on the outside of La Source at Spa, I could do burnouts-in-place forever, but in other places, like on the actual racing surface itself, the car would bog down as if the rear tires were finding unexpectedly huge amounts of grip. So that is certainly strange.
I wouldn’t think there would be enough friction for the front wheel to get that hot, but i wouldnt really know, has anyone ever tested in IRL? it’s is only one wheel though as one will drag more than the other depending on which way you spin. What I find nonsensical is how quick the tyres cool down, doesn’t allow you burn your tyres out by pushing too hard or getting too much wheelspin, your tyres go back to optimum by the next corner
First of all, Forza is not a simulation. While it has some aspects of a simulation it is still only a game and must work within the constraints of the Xbox One system. This limits what can be simulated and at what level that occurs. As an example relating to tire temperatures, a seriously under-inflated tire (15 PSI) should have a center-line temperature lower than both inner and outer temperatures. Over-inflated tires (50 PSI) should have a center-line temperature higher than both inner and outer temperatures. This is a result of deformation of the contact patch. Neither of these conditions is modeled in Forza. The Xbox simply doesn’t have the computational capability to do so and still meet the constraints of making the game playable (60 FPS, etc.). There’s a reason genuine simulators cost hundreds of thousands of dollars and require server farms to run.
So, enjoy the game for what it is but don’t expect it to be something it can’t be. It’s still fun - or it should be if you don’t expect it to do more than it can possibly do.