Automotive Calculators
Engine RPM at a road speed (or speed at an RPM) from tire size, axle ratio and transmission gear ratios, with a table by gear.
OtherLiveeip155:8453Exactvia cdp
AutomotiveGearingRpmTransmissionCalculator
Calls · 30d
1
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far.
$24.31
Verified settled volume
1,175 settlements proven x402 by their on-chain EIP-3009 marker.
$0.020
Listed price
As published in the catalog. Always read the live 402 before paying.
1
Calls · 30d
Upstream's own call count for this endpoint, not ours.
1
Unique payers · 30d
Last called 2026-10-20 20:45Z
—
Upstream on-chain volume
Reported by the source catalog.
Paid to
0xb531320805C5BED1D46AEaDcF4F008FDF172DBDaThe wallet the 402 directs payment to. Its whole payment record — every payer, every chain — is on the merchant page.
Asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Provider
The payTo wallet does not resolve to a registered ERC-8004 agent. That is not a verdict on the service — most of the catalog is unregistered.
Live 402 challenge
Captured by the enrichment pass, not read just now. Prices can change — always read the 402 the endpoint answers with.
{
"error": "Payment required",
"accepts": [
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"scheme": "exact",
"network": "base",
"mimeType": "application/json",
"resource": "https://automotive-calc.x402tookit.com/gear-rpm",
"description": "Engine RPM at a road speed (or speed at an RPM) from tire size, axle ratio and transmission gear ratios, with a table by gear.",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"tire": "26",
"gears": "1:3.59; 2:2.19; 3:1.41; 4:1.00; 5:0.83",
"speed": 60,
"axleRatio": 3.73
}
},
"output": {
"asOf": "2026-10-11T14:38:37.650Z",
"gears": [
{
"rpm": 10387,
"gear": "1",
"gearRatio": 3.59,
"overallRatio": 13.3907
},
{
"rpm": 6336,
"gear": "2",
"gearRatio": 2.19,
"overallRatio": 8.1687
}
],
"speed": 60,
"source": "computed locally",
"reasons": [
"Engine RPM = speed (in/min) / tire circumference x gear ratio x axle ratio; the constant is 1056 / pi = 336 for mph and inches."
],
"summary": "At 60 mph on a 26 in tire with a 3.73 axle, the engine turns 2401 RPM in gear 5 (overall 3.0959:1).",
"verdict": "RPM_COMPUTED",
"degraded": false,
"speedMph": 60,
"axleRatio": 3.73,
"speedUnit": "mph",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"torque converter slip in automatics (RPM runs higher until lock-up) and clutch slip",
"actual loaded tire radius, which is a few percent smaller than nominal diameter",
"…2 more"
],
"tireDiameterInches": 26
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
},
{
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"extra": {
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},
"payTo": "DUPiupXtuox38dcGoXUKer5mAydCzmaHjrbQ66qeEm8s",
"scheme": "exact",
"network": "solana",
"mimeType": "application/json",
"resource": "https://automotive-calc.x402tookit.com/gear-rpm",
"description": "Engine RPM at a road speed (or speed at an RPM) from tire size, axle ratio and transmission gear ratios, with a table by gear.",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"tire": "26",
"gears": "1:3.59; 2:2.19; 3:1.41; 4:1.00; 5:0.83",
"speed": 60,
"axleRatio": 3.73
}
},
"output": {
"asOf": "2026-10-11T14:38:37.650Z",
"gears": [
{
"rpm": 10387,
"gear": "1",
"gearRatio": 3.59,
"overallRatio": 13.3907
},
{
"rpm": 6336,
"gear": "2",
"gearRatio": 2.19,
"overallRatio": 8.1687
}
],
"speed": 60,
"source": "computed locally",
"reasons": [
"Engine RPM = speed (in/min) / tire circumference x gear ratio x axle ratio; the constant is 1056 / pi = 336 for mph and inches."
],
"summary": "At 60 mph on a 26 in tire with a 3.73 axle, the engine turns 2401 RPM in gear 5 (overall 3.0959:1).",
"verdict": "RPM_COMPUTED",
"degraded": false,
"speedMph": 60,
"axleRatio": 3.73,
"speedUnit": "mph",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"torque converter slip in automatics (RPM runs higher until lock-up) and clutch slip",
"actual loaded tire radius, which is a few percent smaller than nominal diameter",
"…2 more"
],
"tireDiameterInches": 26
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
},
{
"asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"scheme": "exact",
"network": "polygon",
"mimeType": "application/json",
"resource": "https://automotive-calc.x402tookit.com/gear-rpm",
"description": "Engine RPM at a road speed (or speed at an RPM) from tire size, axle ratio and transmission gear ratios, with a table by gear.",
"outputSchema": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"tire": "26",
"gears": "1:3.59; 2:2.19; 3:1.41; 4:1.00; 5:0.83",
"speed": 60,
"axleRatio": 3.73
}
},
"output": {
"asOf": "2026-10-11T14:38:37.650Z",
"gears": [
{
"rpm": 10387,
"gear": "1",
"gearRatio": 3.59,
"overallRatio": 13.3907
},
{
"rpm": 6336,
"gear": "2",
"gearRatio": 2.19,
"overallRatio": 8.1687
}
],
"speed": 60,
"source": "computed locally",
"reasons": [
"Engine RPM = speed (in/min) / tire circumference x gear ratio x axle ratio; the constant is 1056 / pi = 336 for mph and inches."
],
"summary": "At 60 mph on a 26 in tire with a 3.73 axle, the engine turns 2401 RPM in gear 5 (overall 3.0959:1).",
"verdict": "RPM_COMPUTED",
"degraded": false,
"speedMph": 60,
"axleRatio": 3.73,
"speedUnit": "mph",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"torque converter slip in automatics (RPM runs higher until lock-up) and clutch slip",
"actual loaded tire radius, which is a few percent smaller than nominal diameter",
"…2 more"
],
"tireDiameterInches": 26
}
},
"maxAmountRequired": "20000",
"maxTimeoutSeconds": 300
}
],
"x402Version": 1,
"alsoAvailable": {
"llms": "https://automotive-calc.x402tookit.com/llms.txt",
"catalog": "https://automotive-calc.x402tookit.com/catalog",
"message": "Automotive Calculators has 10 pay-per-call endpoints (Car math for agents: tire size and speedometer error, gearing and RPM, trip fuel, EV efficiency, towing, depreciation, lease versus buy, engines and braking.), from $0.02 a call. See the full menu and send your agents our way.",
"openapi": "https://automotive-calc.x402tookit.com/openapi.json",
"related": [
{
"url": "https://automotive-calc.x402tookit.com/lease-vs-buy",
"path": "/lease-vs-buy",
"what": "Lease versus buy over the lease term: lease payment from money factor and residual, loan…",
"price": "$0.02"
},
{
"url": "https://automotive-calc.x402tookit.com/stopping-distance",
"path": "/stopping-distance",
"what": "Stopping distance from speed: reaction distance plus braking distance on dry, wet, snow o…",
"price": "$0.02"
},
{
"url": "https://automotive-calc.x402tookit.com/tire-compare",
"path": "/tire-compare",
"what": "Tire dimensions from size codes like 225/45R17, and speedometer and odometer error when y…",
"price": "$0.02"
}
]
}
}Accepts
The payment requirements as published to the catalog. Read the live 402 before paying — a price here is a claim, not a quote.
0.02USDC≈ $0.02 USD
on Base · exact scheme
Pay 0.02 USDC on Base to 0xb531…2DBDa. The signed payment is good for 5 minutes.
- Paid to
- 0xb531…2DBDa
- USD Coin contract
- 0x8335…02913
- Payment window
- 5 minutes
- As published
- 20000 smallest units
20000units
on solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- DUPiup…eEm8s
- Token contract
- EPjFWd…TDt1v
- Payment window
- 5 minutes
20000units
on Polygon · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0x3c49…c3359
- Payment window
- 5 minutes
20000units
on Arbitrum · exact scheme
That figure is in the token’s smallest units. Roundhouse does not hold this contract’s decimals, so it is shown as published rather than converted.
- Paid to
- 0xb531…2DBDa
- Token contract
- 0xaf88…e5831
- Payment window
- 5 minutes
The catalog’s raw entry
[
{
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"amount": "20000",
"scheme": "exact",
"network": "eip155:8453",
"maxTimeoutSeconds": 300
},
{
"asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
"extra": {
"feePayer": "D6ZhtNQ5nT9ZnTHUbqXZsTx5MH2rPFiBBggX4hY1WePM"
},
"payTo": "DUPiupXtuox38dcGoXUKer5mAydCzmaHjrbQ66qeEm8s",
"amount": "20000",
"scheme": "exact",
"network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
"maxTimeoutSeconds": 300
},
{
"asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"amount": "20000",
"scheme": "exact",
"network": "eip155:137",
"maxTimeoutSeconds": 300
},
{
"asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
"extra": {
"name": "USD Coin",
"version": "2"
},
"payTo": "0xb531320805C5BED1D46AEaDcF4F008FDF172DBDa",
"amount": "20000",
"scheme": "exact",
"network": "eip155:42161",
"maxTimeoutSeconds": 300
}
]Extensions
{
"bazaar": {
"info": {
"input": {
"type": "http",
"method": "GET",
"queryParams": {
"tire": "26",
"gears": "1:3.59; 2:2.19; 3:1.41; 4:1.00; 5:0.83",
"speed": 60,
"axleRatio": 3.73
}
},
"output": {
"type": "json",
"example": {
"asOf": "2026-10-11T14:38:37.650Z",
"gears": [
{
"rpm": 10387,
"gear": "1",
"gearRatio": 3.59,
"overallRatio": 13.3907
},
{
"rpm": 6336,
"gear": "2",
"gearRatio": 2.19,
"overallRatio": 8.1687
}
],
"speed": 60,
"source": "computed locally",
"reasons": [
"Engine RPM = speed (in/min) / tire circumference x gear ratio x axle ratio; the constant is 1056 / pi = 336 for mph and inches."
],
"summary": "At 60 mph on a 26 in tire with a 3.73 axle, the engine turns 2401 RPM in gear 5 (overall 3.0959:1).",
"verdict": "RPM_COMPUTED",
"degraded": false,
"speedMph": 60,
"axleRatio": 3.73,
"speedUnit": "mph",
"disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
"notChecked": [
"torque converter slip in automatics (RPM runs higher until lock-up) and clutch slip",
"actual loaded tire radius, which is a few percent smaller than nominal diameter",
"…2 more"
],
"tireDiameterInches": 26
}
}
},
"schema": {
"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": [
"tire",
"axleRatio"
],
"properties": {
"rpm": {
"type": "number",
"description": "Engine RPM, to find the speed instead"
},
"tire": {
"type": "string",
"description": "Tire size like 265/70R17, or a diameter in inches like 28"
},
"gears": {
"type": "string",
"description": "Gear ratios as gear:ratio separated by semicolons, for example '1:3.59; 2:2.19; 3:1.41; 4:1.00; 5:0.83'"
},
"speed": {
"type": "number",
"description": "Road speed (give this, or rpm)"
},
"axleRatio": {
"type": "number",
"description": "Final drive (axle) ratio, 1 to 8, for example 3.73"
},
"gearRatio": {
"type": "number",
"description": "One transmission gear ratio (default 1, direct drive); use gears for several"
},
"speedUnit": {
"type": "string",
"description": "mph (default) or kmh"
}
}
}
},
"additionalProperties": false
},
"output": {
"type": "object",
"required": [
"type"
],
"properties": {
"type": {
"type": "string"
},
"example": {
"type": "object",
"properties": {
"asOf": {
"type": [
"null",
"string"
]
},
"gears": {
"type": [
"array",
"null"
],
"items": {
"type": "object",
"properties": {
"rpm": {
"type": [
"null",
"number"
]
},
"gear": {
"type": [
"null",
"string"
]
},
"gearRatio": {
"type": [
"null",
"number"
]
},
"overallRatio": {
"type": [
"null",
"number"
]
}
}
}
},
"speed": {
"type": [
"null",
"number"
]
},
"source": {
"type": [
"null",
"string"
]
},
"reasons": {
"type": [
"array",
"null"
],
"items": {
"type": "string"
}
},
"summary": {
"type": [
"null",
"string"
]
},
"verdict": {
"type": [
"null",
"string"
]
},
"degraded": {
"type": [
"boolean",
"null"
]
},
"speedMph": {
"type": [
"null",
"number"
]
},
"axleRatio": {
"type": [
"null",
"number"
]
},
"speedUnit": {
"type": [
"null",
"string"
]
},
"disclaimer": {
"type": [
"null",
"string"
]
},
"notChecked": {
"type": [
"array",
"null"
],
"items": {
"type": "string"
}
},
"tireDiameterInches": {
"type": [
"null",
"number"
]
}
}
}
}
}
}
}
}
}Provenance
- Seen in the source catalog
- 2026-10-20 20:45Z
- Last indexed by Roundhouse
- 2026-10-22 06:50Z
- Last enriched (probe, favicon, geo)
- 2026-10-20 22:45Z
- x402 version
- 2
- Max timeout
- 300s
- Liveness probe
- HTTP 402
Hand this page to an agent
Copy the prompt and paste it into Claude, an MCP client or your own agent — it will vet this service and call it over the free read API. No key, no account.
GET api.roundhouseai.io/v0/endpoints
This endpoint's own trailing-30-day call count, as published by the upstream catalog and snapshotted daily. 4 snapshots so far. Verified volume counts only settlements with an on-chain EIP-3009 marker.
Show the promptHide the prompt
Using Roundhouse, look up the x402 service Automotive Calculators and tell me whether it is worth paying: what a call costs, whether the endpoint answered when last probed, and what its payment record actually shows. curl -s 'https://api.roundhouseai.io/v0/endpoints?q=Automotive%20Calculators' curl -s 'https://api.roundhouseai.io/v0/merchants/<the payTo wallet returned above>' Then call it: read the price from the live 402 at https://automotive-calc.x402tookit.com/gear-rpm, never from a cached figure, and pay with an x402 client. The /v0 API needs an API key (`authorization: Bearer rh_live_…`) on everything except /v0/unified* and /v0/endpoints. Either pay over x402 (mint a personal key for $0.01 at GET https://api.roundhouseai.io/v0/test/x402), or ask me for an organization key, which I create at https://roundhouseai.io/dashboard/connections. If you have neither, ask before going further. If you do not have Roundhouse tools or skills installed, read https://roundhouseai.io/skill.md first — it is the whole procedure.