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Ideal for automotive and motorsport apps, tyre shops and fitment tools, modding and restomod planning, and vehicle configurators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. 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The compare endpoint takes an original and a replacement tyre size and works out the change in overall diameter and the resulting speedometer and odometer error — so you know how much faster you are really going than the dial shows after a tyre change. The gear endpoint computes a gear ratio from ring and pinion tooth counts, or the road speed from engine RPM, total gear ratio and tyre size. Everything is computed locally and deterministically, so it is instant and private. Ideal for automotive and motorsport apps, tyre shops and fitment tools, modding and restomod planning, and bike/car configurators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is tyre and drivetrain maths; for vehicle specs by VIN use a vehicle-database API."},"meta":{"timestamp":"2026-06-03T17:42:03.105Z","request_id":"1bb3fb99-314d-4939-b45d-9714d816b32e"},"status":"ok","message":"Meta","success":true}}}},"401":{"description":"Missing or invalid x-oanor-key header"},"402":{"description":"Active subscription required"},"429":{"description":"Rate-limit or monthly quota reached"},"502":{"description":"Upstream did not respond"}}}}},"x-oanor-pricing":[{"slug":"free","name":"Free","price_cents_month":0,"monthly_call_quota":8735,"rps_limit":2,"hard_limit":true},{"slug":"starter","name":"Starter","price_cents_month":1025,"monthly_call_quota":18250,"rps_limit":8,"hard_limit":true},{"slug":"pro","name":"Pro","price_cents_month":3015,"monthly_call_quota":233500,"rps_limit":20,"hard_limit":true},{"slug":"mega","name":"Mega","price_cents_month":6815,"monthly_call_quota":1210000,"rps_limit":50,"hard_limit":true}],"x-oanor-marketplace-url":"https://www.oanor.com/api/tirecalc-api"}