Complex sentence: Modern road tourers are usually built around 700C (622mm) wheels which have rims the same diameter as a road (racing) bicycle, but typically the touring bike will have wider rims and more clearance in the frame for wider tires.
Split into simpler sentences: Modern road tourers are usually built around 700C (622mm) wheels which have rims the same diameter as a road (racing) bicycle. However, the typical road touring bike will have wider rims and more clearance in the frame for wider tires.