If you stretch the Tyco sized tyres too much, they can lose their flatness across the surface, which wouldn't be good, although I think they'd soon bed down. Maybe that's where the truer is useful?
The idea of using the LL sizes on the big hubs is a good one. You get three sizes, the thinnest is as thin as the .418s, if not a little thinner. Unfortunately Frank only does them in black in the softer compound, but worth a go.
Once you've got some hub and tyre combos and you start testing, it's quite easy to tell when you're too low (very grippy > but too hot > slows down > smell of smoke > flames > call fire brigade) or too high (well fast, but too crashy). You should find the hub size you need quite easily and then have 2-3 tyres sizes to go with them. So maybe start with one set of each hubs and you can then buy a few more of the size that works best.
Then sort out the gearing. That's more about your driving style and the characteristics of the layout. I reckon the first thing is to change the gearing to adapt the car to different tracks. Getting the car higher
as well is definitely better for fast tracks, especially ovals. Really twisty tracks can do with dropping the tyre height because you don't need the top speed so much.
That initial testing is for finding a baseline for that car on that track. You really need to do that on an EAHORC or WHO track. But maybe we could set up a big straight somewhere in Brighton for a test session? I can
just do a 22 foot straight in my house. My 'stiffened' Mega-G needs a run out
