Tire Size & Wheel Fitment API FAQ | Questions About Coverage, Pricing & Limits

General

Overview of the Tire Size API and who it's built for.

Provides accurate, up-to-date tire fitment data for vehicles across a wide range of makes, models, years, and trims
A single request returns the exact OEM tire size for any supported vehicle — the full size string plus its width, aspect ratio, and rim diameter
Built for tire retailers, automotive platforms, fleet management systems, and e-commerce stores that need reliable fitment data without building their own database

Tire retailers — power your "find tires by vehicle" search widget
E-commerce platforms — filter and recommend tires for any vehicle
Fleet managers — automate tire spec lookups across a mixed fleet
Automotive apps — add fitment data without a database of your own
Developers — integrate tire data into any product via a simple REST API

Yes — visit our live API demo to run real searches by vehicle or tire size without creating an account
The Free tier gives you 250 tire lookups a month at no cost — plus 250 more to start, and no credit card required

All responses are in JSON format over HTTPS — standard REST conventions
Full OpenAPI 3.0 spec available in both YAML and JSON — import directly into Postman, Insomnia, or any code generator

We target 99.9% uptime — check real-time status at /api/health
Business customers can request a custom SLA — contact us to discuss

Help Center — step-by-step guides and troubleshooting for common issues
Contact form — we respond within 24 hours
/api/health — check if there is an ongoing incident

Tip: Check the Help Center first — most authentication and 404 issues are solved there in under a minute.

A 429 Access temporarily throttled or 403 Access suspended response means bulk-access patterns were detected on your key under our Terms of Use §7.1
Stop the bulk job first. A throttle lifts by itself once traffic on the key has been quiet for a while — it does not clear simply because time has passed, so a script that keeps retrying at speed stays throttled for as long as it runs
Repeated throttles require progressively longer quiet periods, and after several the key needs a support review before it resumes
Suspension is always reviewed by a person and is lifted by contacting support
See the Help Center troubleshooting guide for the full walkthrough

Note: These terms apply the same way on every plan, so changing plans is not the fix. If your workload genuinely needs bulk data, ask us about a commercial data license.

Pricing & Plans

Everything about plans, billing, limits, and cancellation.

Free

$0 / month

250 lookups/mo

Starter

$40 / month

5,000 req/day

Pro

$70 / month

50,000 req/day

Business

$150 / month

80,000 req/day

See exact pricing on our Pricing page

Completely free — no credit card required
250 tire lookups per month, plus a one-time 250-lookup bonus when you sign up — 500 in your first month. Resets on the first of each month (Eastern Time, America/Toronto)
Only the lookup that resolves a tire size counts — /by_vehicle/tiresize and /tire_dimensions. Browsing year, make, model and trim is free and unlimited
Enforced from 15 September 2026. Until then your usage is reported at GET /api/v1/usage and on your dashboard, but nothing is refused
A fair-use burst guard also applies — 300 requests/day and 100 requests/hour, resetting at midnight and the top of each hour (Eastern Time). It is there to stop bulk jobs, not to shape normal use
Designed for development, testing, and small projects
Upgrade any time from your dashboard when you need more volume

Note: The Free plan is also rate-limited per IP. For production use, upgrade to Starter or higher.

You'll receive a 429 Too Many Requests response for any requests over your limit
Quota resets at midnight Eastern Time (America/Toronto) automatically — no action needed
Monitor usage from your dashboard or upgrade to avoid interruptions in production

Four endpoint groups carry a monthly quota in addition to — not instead of — your plan's daily request limit:
/by_vin/{vin} — Free 10, Starter 500, Pro 5,000, Business 20,000 (Free also gets a one-time 50-lookup welcome bonus)
/reverse_lookup — Free 10, Starter 5,000, Pro 20,000, Business 60,000 (Free also gets a one-time 10-lookup trial bonus)
/search_allsizes — Business 500; not available on other plans
/by_vehicle/tiresize and /tire_dimensions — Free 250 (plus a one-time 250-lookup bonus); unmetered on paid plans. Only the lookup that resolves a tire size counts — browsing year, make, model and trim is free. Enforced from 15 September 2026; until then your usage is reported but nothing is refused.
Monthly quotas reset on the first of each month (Eastern Time, America/Toronto); daily limits reset at midnight Eastern Time
Everything else — the /by_vehicle cascade steps (make, model, trim), /by_size, /oem_specs and the reference lists — runs on the daily limit only

Tip: Call GET /api/v1/usage or read the X-VIN-Quota-*, X-RevLookup-Quota-*, X-AllSizes-Quota-* and X-Fitment-Quota-* response headers to see exactly what you have left.

GET /api/v1/search_allsizes returns every distinct tire size in the database in one cached call, and is available on the Business plan only
Free, Starter, and Pro keys receive 403 Business subscription required for this endpoint
Business includes 500 size-catalog calls per month — the response is cacheable for an hour, so a single daily refresh is usually plenty
On any plan you can still build a size list from /search_allwidth and /by_size/*

Billed monthly on the date you first subscribed
Receipt sent by email after each charge
View full billing history in your account dashboard

Cancel anytime from your dashboard under Plans → Cancel Subscription
Keep your current plan access until the end of the billing period — no immediate cutoff
Account reverts to the Free tier automatically after the period ends

Go to your dashboard and click Plans
Upgrades take effect immediately
Downgrades apply at the start of the next billing cycle — you keep current limits until then

Refund requests are evaluated case by case
If you were charged in error or experienced significant downtime on our side, contact us and we'll make it right

We consider discount requests on a case-by-case basis
Reach out with a brief description of your project and we'll see what we can do

Technical

Authentication, integration, caching, and developer tools.

Pass your API key as a request header: x-api-key: YOUR_API_KEY
Do not include it as a URL query parameter — it will be rejected
Get your key from your account dashboard under the API Key tab

Works with any language that can make HTTP requests — it's a standard REST API
Our API docs include ready-to-use examples for JavaScript, Python, and cURL
The OpenAPI spec can auto-generate client code for Go, PHP, Ruby, Java, C#, and more via OpenAPI Generator

Technically yes, but strongly not recommended
Client-side calls expose your API key in the page source — it can be scraped and abused

Best practice: Proxy requests through your own backend. Your backend holds the key, the browser never sees it. This also lets you add your own caching layer.

CORS is enabled for registered domains
Need a specific domain added? Contact us with your domain and we'll add it to the allowlist
Direct client-side API calls are not recommended for security reasons (see above)

Tire fitment data changes rarely — caching is highly recommended
Lookup lists (all makes, years, widths) — cache for 24 hours or longer
Vehicle fitment data — cache for 7 days safely
Caching reduces daily request usage, speeds up your app, and prevents hitting rate limits during traffic spikes

OpenAPI YAML — import into Postman, Insomnia, etc.
OpenAPI JSON — for automated pipelines and code generators
Explore and test all endpoints interactively in our Swagger UI directly in the browser

Production: https://tire.vdim.app/api/v1
Documentation: https://tire.vdim.app/api/docs
Health check: https://tire.vdim.app/api/health
All endpoints require HTTPS — HTTP requests are not accepted

Yes — GET /api/v1/by_vin/{vin} decodes a 17-character VIN and returns the vehicle's factory tire sizes
VIN lookups have a monthly quota by plan: Free 10, Starter 500, Pro 5,000, Business 20,000
Free plans get a one-time welcome bonus of 50 VIN lookups to try the feature
The quota resets on the first of each month (America/Toronto); track it via the X-VIN-Quota-Remaining response header or /api/v1/usage

Yes — GET /api/v1/search_allsizes returns every distinct tire size in the database, with no parameters required
Available on the Business plan only, metered at 500 calls per month
Returns size strings only — no vehicle or fitment linkage — so it's built for seeding a size picker or your own sizing engine
Responses are cacheable for an hour (Cache-Control: public, max-age=3600), so one refresh a day is normally enough

Yes — GET /api/v1/oem_specs?year=2021&make=Ford&model=F-150 returns the factory OEM specifications for a vehicle: lug-nut torque, load index, speed rating, and the XL flag
year, make and model are required; trim is optional — leave it out to get every trim for the vehicle
A torque_ft_lb of null means the figure is not published for that fitment — consult the vehicle manual. It is not zero, and it does not mean the lookup failed: we withhold a number whenever two upstream sources disagree, because under-torque is the wheel-loss failure mode and a wrong figure is worse than none. Coverage is about 72% of fitments as of 2026-08-22, up from 45% a week earlier, and still growing
Read fastener_type before you display the number — it is "lug_nut" or "center_lock" (null when the torque is null). Centre-lock hubs use a single central nut at a much higher torque, so don't blanket-label the value "lug nut torque"
Requires a paid plan (Starter, Pro, or Business) — Free keys get 403 Paid subscription required. There is no monthly quota — calls come out of your daily request limit. Unlike /tire_dimensions, which counts against the monthly fitment allowance, a paid plan is the only extra requirement here
Responses are not cached, since the data is specific to the vehicle you asked for

GET /api/v1/usage returns a vinQuota, reverseLookupQuota, allSizesQuota, and fitmentQuota block, each with monthlyLimit, monthlyUsed, monthlyRemaining, and resetTime
Every quota'd response also carries headers: X-VIN-Quota-Limit / -Remaining / -Reset, and the equivalent X-RevLookup-Quota-*, X-AllSizes-Quota-* and X-Fitment-Quota-* families
While a one-time bonus is still available you'll also see X-VIN-Bonus-Remaining, X-RevLookup-Bonus-Remaining or X-Fitment-Bonus-Remaining
allSizesQuota.monthlyLimit is null on plans without size-catalog access

Tip: The -Reset headers are Unix timestamps — use them to schedule retries instead of polling.

All error responses use a consistent JSON structure: { "error": "...", "status": 401, "timestamp": "..." }
401 — invalid or missing API key
403 — the endpoint requires a higher plan, or access has been restricted under the fair-use terms
404 — no data found for that vehicle
429 — a limit was hit; branch on the error field to tell them apart: "Daily API request limit exceeded", "Monthly VIN quota exceeded", "Monthly reverse-lookup quota exceeded", "Monthly size-catalog quota exceeded", "Monthly fitment lookup quota exceeded", or "Access temporarily throttled"
500 — server error; retry after a short delay — these are transient

Tip: Honour the Retry-After header when it is present, and use exponential backoff otherwise.

Data & Coverage

What's in the database, how accurate it is, and how to handle gaps.

Covers passenger vehicles, SUVs, and light trucks for the North American market
Use /search_allmake to get the full list of supported makes
Use /year_range?make=Toyota to check year coverage for a specific make

Reflects OEM (Original Equipment Manufacturer) specifications — the sizes vehicles ship with from the factory
Data is sourced and verified from manufacturer documentation
Found a discrepancy? Report it and we'll investigate and correct it

Updated as new model year data becomes available — typically annually for new model years
Ongoing corrections and additions throughout the year
Follow our blog for update announcements and new endpoint releases

No — the API covers OEM fitment data only (what the vehicle came with from the factory)
Does not include aftermarket wheel sizes, lifted fitments, plus-sizing recommendations, or winter tire packages
This scope keeps the data reliable and unambiguous

Use /search_allmake to confirm the exact make spelling — spelling and spacing matter (e.g. Land Rover not Land-Rover)
Try omitting the trim parameter to get all trims for that model
If the vehicle is genuinely missing, contact us with the year, make, model, and trim — we'll prioritize adding it

Different trim levels often ship with different wheel and tire sizes
Example: a base LE trim may use 17" wheels while the XSE uses 18"
The API returns all trims — always filter by trim for accurate fitment data

235 — section width in millimeters (how wide the tire is)
45 — aspect ratio (sidewall height as % of width)
R — radial construction
18 — wheel diameter in inches
The API returns separate fields (width, aspectratio, diameter) as well as the combined tiresize string

VIN decoding is backed by the NHTSA vPIC dataset, the U.S. government's public vehicle product information catalogue
NHTSA publishes a new snapshot each month, and we refresh against it monthly — so newly registered VIN patterns are picked up shortly after they're published
The decoded year / make / model is then matched against our OEM fitment data to return the factory tire sizes
If a VIN decodes but returns no tire sizes, the vehicle isn't in our fitment coverage yet — let us know and we'll look at adding it

Our Terms of Use §7.1 set out what the API may not be used for. In plain terms, you may not:
Systematically harvest, crawl, or bulk-download the data, including by enumerating or iterating across endpoints to sweep the catalogue
Reconstruct a substantial portion of our tire-size or fitment database — including gradually over time or in aggregate across multiple accounts, keys, or IP addresses
Redistribute, resell, or publish responses as a standalone dataset
Access the fitment endpoints other than in response to genuine, human-initiated activity in your own application — no crawlers, headless browsers, or scheduled jobs iterating across vehicles or sizes
Circumvent rate limits, per-endpoint quotas, or other access controls
These rules apply identically on every plan, including Business. We monitor access and can throttle or suspend keys that breach them.

Need bulk data? Normal application use will never come close to these lines. If you genuinely need bulk or full-catalog data, contact us about a commercial data license — we're happy to help you get it the right way.

Frequently Asked Questions

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