Like Mr B said there are always the 23" XL wheels. I have bought four so far and have one set with new tyres. Unfortunately as MrB pointed out. Tyre selection isn't great. I'm pretty sure there is only one mass produced tyre and that is the Bridgestone TW-9...... Speedway bikes also use 23" front wheels so you can choose from speedway tyres. I've seen a really cool 23" speedway tyre but I doubt they would have a hard compound tyre available (I have a contact number and will be enquiring soon)...... I did see a very very cool looking 23" vintage style tyre from a Chinese disrtributor website, but as it was in Chinese I didn't follow it up....... Hope that helps, and I can't see what you come up with next.