I'm really not sure what you're pursuing here as a whole? Seems to be a whole lot of effort for nothing really

I think it's pretty clear that the tyre wear itself has no direct physical influence on the car's performance (in LFS). All the factors you're speculating about here are far to small to have any serious impact on laptimes, compared to the uncertainty factor that is human control, or other actually big factors like tyre temperature or fuel weight. If there was an artefact, a physics oddity, then somehow it would have to be big enough that untalented drivers (relatively speaking) benefit from it, too, for it to be "noticed" so widely. And if it were that big, you'd see all world record laps taking 60+ laps beforehand to wear down the tyres to get this then very tangible advantage of having worn tyres, and I'm pretty sure hotlappers do anything to set a WR

Honestly, I think it's more to do with ones mind than having an actual physical reason. You want to believe... no, you know that a worn tyre makes you faster so in the end you are faster. Suddenly in your mind the worn tyre actually made you faster, whereas it was probably just you believing in yourself resulting in better driving. And with that you have the self-reinforcing "evidence" of worn tyres making someone faster, where there can hardly be found any measurable effect of tyre wear itself.

Comparisons of LFS to real life are also somewhat useless. While LFS is quite good and complex in general, if you start going into the details you just notice more and more areas that very much matter for racing are only very roughly approximated if simulated at all. Tyre heat and wear is (officially) a very WIP part of the simulation, with most behaviour being barely more than educated guesses. I could now list all the obvious deficiencies of LFS' tyre model, but really there's no point. Making a fully abstract model of a tyre where in the end the correct behaviour just falls into place is, while noble, not really realistic in terms of being a reachable goal either.

Right now, I think LFS in terms of realism is so close, yet so far.

Quote from Neilser :

Not sure why a larger tyre should have less resistance, but certainly the sidewall argument seems sound.

Perhaps it is due to larger tyres generally being used to support larger weights, so are made stiffer, thus flex less, or that larger radii wheels will be less affected by the small bumps that are present on any non-smooth surface.

Quote from AndroidXP :

Honestly, I think it's more to do with ones mind than having an actual physical reason. You want to believe... no, you know that a worn tyre makes you faster so in the end you are faster. Suddenly in your mind the worn tyre actually made you faster, whereas it was probably just you believing in yourself resulting in better driving. And with that you have the self-reinforcing "evidence" of worn tyres making someone faster, where there can hardly be found any measurable effect of tyre wear itself.

Nah, the lesser heat capacity definitely makes a difference - if your tyres can cool between the corners you'll be able to push more than with a full tread... For example, the temperature will steadily increase in those long fast corners of KY GP on fresh rubber - a worn tyre can cool down even on those short straights...

excuse, one question - why do you think worn tyres can make a run quicker? Because of some lad who took his time to wear them down just before WR attempt?... maybe it made him... lucky

Interesting but I've always assumed that the contact patch would get longer, and thus the angle would remain similar. That's also assuming the tyre were just as vertically stiff, so would vertically deform as far. I think that the extra rubber makes the tyre stiffer, leading to less deformation, thus less hysteresis.

Quote from Whitmore :

After all, a smaller dia tyre at 50 psi will have a lower rolling resistance than a bigger tyre at 10 psi.

Agreed (from a general standpoint). The way I work my tyre deformation maths though, a larger tyre gives me a longer contact patch, all other things being equal. It makes sense, it must be part of the reason top fuel dragsters run such huge tyres (the other being the lowering of angular velocity, to handle the speeds they reach without the tyre tearing apart).