{"uid":"cap_cabrmkWDjV9y5lznscx9F","slug":"automotive-calculators-tire-size-comparison-speedometer-error-1b9f2e02","name":"Automotive Calculators – Tire Size Comparison & Speedometer Error","description":"Tire dimensions from size codes like 225/45R17, and speedometer and odometer error when you change to a different size.","url":"https://automotive-calc.x402tookit.com/tire-compare?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["currentSize"],"properties":{"newSize":{"type":"string","description":"Replacement size to compare"},"currentSize":{"type":"string","description":"Tire size now, for example 225/45R17 or 31x10.5R15"},"indicatedMph":{"type":"number","description":"Speed shown on your speedometer in mph, 5 to 200 (default 60)"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"asOf":{"type":["null","string"]},"source":{"type":["null","string"]},"current":{"type":["null","object"],"properties":{"size":{"type":["null","string"]},"widthMm":{"type":["null","number"]},"rimInches":{"type":["null","number"]},"diameterMm":{"type":["null","number"]},"sidewallMm":{"type":["null","number"]},"diameterInches":{"type":["null","number"]},"revolutionsPerKm":{"type":["null","number"]},"aspectRatioPercent":{"type":["null","number"]},"revolutionsPerMile":{"type":["null","number"]},"circumferenceInches":{"type":["null","number"]}}},"reasons":{"type":["array","null"],"items":{"type":"string"}},"summary":{"type":["null","string"]},"verdict":{"type":["null","string"]},"degraded":{"type":["boolean","null"]},"actualKmh":{"type":["null","number"]},"actualMph":{"type":["null","number"]},"disclaimer":{"type":["null","string"]},"notChecked":{"type":["array","null"],"items":{"type":"string"}},"speedTable":{"type":["array","null"],"items":{"type":"object","properties":{"actualMph":{"type":["null","number"]},"indicatedMph":{"type":["null","number"]}}}},"replacement":{"type":["null","object"],"properties":{"size":{"type":["null","string"]},"widthMm":{"type":["null","number"]},"rimInches":{"type":["null","number"]},"diameterMm":{"type":["null","number"]},"sidewallMm":{"type":["null","number"]},"diameterInches":{"type":["null","number"]},"revolutionsPerKm":{"type":["null","number"]},"aspectRatioPercent":{"type":["null","number"]},"revolutionsPerMile":{"type":["null","number"]},"circumferenceInches":{"type":["null","number"]}}},"indicatedMph":{"type":["null","number"]},"speedErrorMph":{"type":["null","number"]},"speedometerFactor":{"type":["null","number"]},"diameterDifferenceMm":{"type":["null","number"]},"odometerErrorPercent":{"type":["null","number"]},"diameterDifferencePercent":{"type":["null","number"]},"effectiveGearingChangePercent":{"type":["null","number"]}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Ct_Z_kGD36H5RRIDlO3KJ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Calculates physical dimensions for a tire size code and computes speedometer/odometer error when switching to a different tire size","exampleAgentPrompt":"I'm upgrading from 225/45R17 to 235/40R18 tires — can you compare those two sizes and tell me what my actual speed will be when my speedometer reads 65 mph?","exampleUseCases":[{"title":"Lift kit tire fitment check","prompt":"I'm putting 285/75R16 tires on my truck that currently runs 265/70R16. What are the size differences and how far off will my speedometer be at 60 mph indicated?"},{"title":"Metric to imperial tire size conversion","prompt":"What are the actual dimensions of a 31x10.5R15 tire — height, width, sidewall, circumference and revolutions per mile?"},{"title":"Speedometer recalibration after wheel upgrade","prompt":"I switched from 205/55R16 to 225/50R17 rims and tires. Can you calculate exactly how much my odometer will be off and what my true speed is at each 10 mph increment on my speedometer up to 80 mph?"}],"resultDescription":"Returns parsed physical dimensions for the current tire size (width in mm, sidewall in mm, rim diameter in inches, overall diameter in mm and inches, circumference in inches, revolutions per mile and per km), and if a replacement size is provided: the same dimensions for the new size, the percentage difference in diameter, actual vs indicated speed at the given mph, a speed correction table across a range of indicated speeds, a verdict on compatibility, and any warnings or disclaimers.","failureModes":["Invalid or unrecognized tire size format returns an error or null dimensions","Missing required currentSize parameter returns a 400-level error","Malformed size code (e.g. missing aspect ratio) may yield null fields","indicatedMph outside 5–200 range may be rejected or clamped","Network timeout or upstream service unavailability returns 5xx"],"whenToPreferThis":"Use this endpoint when you need precise tire dimension calculations from standard metric (225/45R17) or flotation (31x10.5R15) size codes, or when comparing two tire sizes to quantify speedometer and odometer error. Prefer this over generic search when you need structured numeric outputs (diameter, revolutions per mile, actual speed) that can be used programmatically downstream.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T07:04:58.548Z","isFirstParty":false,"canonicalSlug":"automotive-calculators-tire-size-comparison-speedometer-error-1b9f2e02"}