I've got to say I wasn't that impressed when I heard that Studio 397 are considering rF1 tyres. That being said I can see the benefits of having them available for modders to begin with if they are just starting out.
One of the unique selling points of rF2 is the complex tyres. When I think back to when I started racing on rF2, I quickly realised how bad a driver I was. It's taught me to be a much more careful driver, and it really makes you think about tyres which makes the whole thing more immersive. I hate to use the cliché but I do feel this is a backward step.
What I'd much prefer to see is Studio 397 tasking someone (a tyre specialist) with making a 'tyre bank' or a 'tyre pool'. A range of modern and historic tyres in different sizes that modders could use, and edit if needed. As a casual modder myself, I have made a few street cars, only for tyres to be the stumbling block, so a compromise has to be made. I'd personally love to sit down and learn how to make a tyre from scratch, but I simply don't have the time to do so. I also know a lot of other modders who are the same.
I'm also sceptical when 'old modding groups' are mentioned. I know for a fact that a lot of these have either moved to different platforms, or just given up the whole scene due to other commitments. The ones who are still modding for rF2 are the purists who strive for realism, and aren't influenced by gimmicks or fancy graphics.
So, in short, I'd say use the TBC model as a starter for new projects just so modders can get their cars working in game, but support and encourage them to use the new TGM model, and provide a lot more examples to get them started with it.