A tire marking is a compact specification, not just a size name. Before replacing a scooter tire, photograph the complete sidewall marking and compare it with the vehicle maker’s recommendation.
Example: 90/90-12
- 90 is the nominal section width in millimetres.
- 90 is the aspect ratio: the sidewall height is roughly 90% of the width.
- – indicates a bias construction in many common markings; an R indicates radial construction.
- 12 is the rim diameter in inches.
Real dimensions vary by design and approved rim width, so treat the numbers as a starting point rather than a promise of exact measured width.
Other markings matter
Look for load index, speed symbol, tubeless or tube-type construction, rotation direction and the production date code. A tire that fits the rim can still be wrong for the scooter’s load, speed, brake clearance or fender space.
How to choose safely
Match the complete marking, load rating and construction. Check front/rear position, valve and tube requirements, rim width, suspension clearance and the combined rider-plus-payload requirement. Do not fit a wider tire only for appearance: it can change steering, rubbing clearance and efficiency.
Keep both tires inflated to the maker’s pressure guidance and inspect for cuts, bulges, uneven wear and embedded objects. Replace a damaged or aged tire even when the tread still looks deep.