This issue has persisted since Forza Motorsport 3. The Motegi Racing SP10 wheels have an inaccurate model. They are not concave enough and the centre piece is way too small. It seems that they were modeled for a much larger diameter than they were ever offered in.
![Motegi 4](https://global.discourse-cdn.com/forza/original/4X/0/0/4/0044371f4bf79c0cf08df092a548e7208bbb7532.jpeg)
The model in Forza Motorsport is the same.