I’m currently looking into the possibility of producing a range of S7 driving wheels in sizes equating to 3ft to 4ft3. I have a UK based supplier for the tyres and I should have a sample 3ft6 tyre in my hand by the end of next week. My intention is to 3D print the centres so that they can fit onto either Slater’s 1/8th or 3/16th standard axles.