Actually, there are not so many wheel+tyre combinations.
I find these assemblies quite a natural thing to have in the library.
For example, in my real LEGO collection I usually don't disassemble them.
I have 2 points against your suggestion of the !HELP line:
(a) It is abusing a free-text syntax element and assigns special meaning to it.
If something like that really should be our solution to this question, then we should
add a unique meta statement for that purpose.
(b) In case we did that, we would be re-creating something new which is already there:
assemblies of wheels+tyre. These can perfectly well be modeled with the syntax elements
we already have.
I would say that 20 or something of these assemblies wouldn't hurt our library.
I would see them as a win.
The reason to have them is:
(i) it is very tedious and a quite numb task to find the fitting tyres for each wheel again and again
(ii) nearly every assembly containing a wheel plus tyre would anyway create a submodel of them two,
so having that readily combined in the library saves the users from that
(iii) some wheels or tyres have slightly but wrong offsets, like 44772.dat, a big wheel with an offset misplaced by 3 in Z direction.
all these little oddities can carefully be taken care of by the wheel+tyre assemblies readily, like I for example did with 44772c01
I find these assemblies quite a natural thing to have in the library.
For example, in my real LEGO collection I usually don't disassemble them.
I have 2 points against your suggestion of the !HELP line:
(a) It is abusing a free-text syntax element and assigns special meaning to it.
If something like that really should be our solution to this question, then we should
add a unique meta statement for that purpose.
(b) In case we did that, we would be re-creating something new which is already there:
assemblies of wheels+tyre. These can perfectly well be modeled with the syntax elements
we already have.
I would say that 20 or something of these assemblies wouldn't hurt our library.
I would see them as a win.
The reason to have them is:
(i) it is very tedious and a quite numb task to find the fitting tyres for each wheel again and again
(ii) nearly every assembly containing a wheel plus tyre would anyway create a submodel of them two,
so having that readily combined in the library saves the users from that
(iii) some wheels or tyres have slightly but wrong offsets, like 44772.dat, a big wheel with an offset misplaced by 3 in Z direction.
all these little oddities can carefully be taken care of by the wheel+tyre assemblies readily, like I for example did with 44772c01