Lets not get off topic on how the tires look when worn. That is a completely different topic.
I do agree that it would be nice to balance the classes. But it is not going to be simple. I think I understand what Gimpster is saying, reduce some of the variables so that balancing can happen more easily. With that, I would agree. However, I think by doing this, you will greatly reduce the unique feel of each car. Sure, FWD and RWD difference will be there, but I bet you will lose some of the unique feel of the cars. I love the different feel in the cars and would like to keep as much of that as possible.
A lot of real racing series use different methods to balance cars. Weight restrictions, inlet air restrictors to reduce HP (but generally not a HP limit), fender flair size, wheel size, displacement limits on engines... only complete spec series use HP limits per say. ALMS or LMS uses weight limits, air restrictors, and other things that preserve the unique aspects of each car, whilst trying to make it possible for all car types to be competitive. We have more of a controlled environment so we can balance classes without having to lose the unique feel of each car. A XR GT should be heavier than a XF GTi. The HP output should be different. That is what makes the cars unique and more like the real world. What I am afraid your suggestion would lead to is a single car class that just happens to have FWD, RWD and AWD options with different shapes, but no real character differences in the feel of the cars.
The issue I have with the tires revolves around wear rates and temp.
With R2 tires, in most cases it is almost impossible to wear them out. You reach an overtemperature condition long before you wear the tires out. The temperature gets to the point where they are undriveable. It might be that we all drive the cars too hard and slide them around too much compared to the real world. However, as it sits now, R2's are really only good for qualifying runs or a couple of hotlaps before they are so hot, you can't drive on them. This seems unreasonable to me. R2's should be really good for 2 laps, then drop in grip a lot and then hold steady over the next x laps until nearing the end of the available tread, they start trailing off again quickly. This should be associated with the tread remaining, not just a function of temperature like we have now. If you don't overdrive the R2's during a race, you can keep the temps down, but then you are as slow if not slower then the cars running R3 tires. There just seems to be something wrong with this.
Second, I think excess camber should not necessarily cause overtemp on the inside patch after a lap like it does. However, after a few laps, you should definitely see a lot more wear on the inside patch compared to the rest of the tire. Yes, it should be hotter too, but not overtemp (unless you are spinning tires or sliding a lot).
My point is that real tires should not be going to an overtemp condition so easily.
For the road type tires, we have a bit of a problem. They don't wear very fast... just like real life. You can run a 50 lap race at BL and you should still have tread left. However, road tires will get hot easier and become undriveable if you do try and overdrive the tires. I don't think we see this enough with the road tires. Club racers often use the same tires for several races, or even a whole season. I doubt we could model this in LFS, which is OK, but we should do something about the heating.
So, I guess the tires come down to the issues of the race tires overheating too quickly or easily and not wearing quickly enough, and the road tires not overheating enough when being over-driven.