1. Go to account-tire.vdim.app/signin/signup
2. Enter your email, company or organization, country, and a password, then click Sign up (or continue with GitHub)
3. Click the confirmation link we email you — it signs you in and opens your dashboard
4. Answer the short profile question (how you heard about us; company website is optional) and your API key appears

1. Every account starts on the Free plan — no checkout or card needed
2. Your API key is created automatically and shown in the API Key card on your dashboard, with a ready-to-copy first request
3. Copy the key — you'll include it in every request as the x-api-key header
4. To upgrade, open Pricing and choose Starter, Pro, or Business

• You can also test the API using our live demo before signing up

• Replace YOUR_API_KEY with your key and run this in your terminal:

curl -H "x-api-key: YOUR_API_KEY" \
  "https://tire.vdim.app/api/v1/tire_dimensions?year=2023&make=Toyota&model=Camry&trim=LE%20AWD"

• You should get a JSON response with the vehicle's tire dimensions
• If you get a 401, double-check the header name is exactly x-api-key

• Use the /tire_dimensions endpoint with year, make, model, and trim:

GET /api/v1/tire_dimensions?year=2022&make=Toyota&model=Camry&trim=LE

• All four parameters are required — omitting any of them returns 400 Bad Request listing what's missing
• Use /search_allyear and /search_allmake first to get valid values for dropdowns, then /by_vehicle/model and /by_vehicle/trim to narrow down
• Optionally add tiresize to filter the returned dimensions to one specific size

• Search by aspect ratio — returns matching tire sizes for a given width:

GET /api/v1/by_size/aspectratio?width=225

• Search by diameter — narrows results by width and aspect ratio:

GET /api/v1/by_size/diameter?width=225&aspectratio=45

• Send a 17-character VIN and get the decoded vehicle plus its factory tire sizes:

GET /api/v1/by_vin/1HGCM82633A004352

• VIN lookups use a monthly quota separate from your daily limit: Free 10, Starter 500, Pro 5,000, Business 20,000 (Free plans also get a one-time 50-lookup welcome bonus)
• Track remaining lookups via the X-VIN-Quota-Remaining response header or GET /api/v1/usage; the quota resets on the first of each month (America/Toronto)

• Use /reverse_lookup with a full size string, or with the individual dimensions:

GET /api/v1/reverse_lookup?tiresize=225/60R16
GET /api/v1/reverse_lookup?width=225&aspectratio=60&diameter=16

• Returns a vehicles array of year / make / model / trim combinations that use that size
• Reverse lookups use a monthly quota separate from your daily limit: Free 10, Starter 5,000, Pro 20,000, Business 60,000 (Free plans also get a one-time 10-lookup trial bonus)
• Track it via the X-RevLookup-Quota-Remaining header or GET /api/v1/usage; it resets on the first of each month (America/Toronto)

• Business plans can pull every distinct tire size in the database in a single call — no parameters needed:

GET /api/v1/search_allsizes

• Returns size strings only (no vehicle or fitment linkage) — built for seeding a size picker or your own sizing engine
• Business plan only — other plans receive 403 Business subscription required
• Metered at 500 calls per month, reported via the X-AllSizes-Quota-* headers
• Cached for an hour (Cache-Control: public, max-age=3600), so one refresh per day is normally plenty

• Use /oem_specs with year, make and model — all three are required:

GET /api/v1/oem_specs?year=2021&make=Ford&model=F-150&trim=XLT SuperCrew
GET /api/v1/oem_specs?year=2021&make=Ford&model=F-150

• trim is optional — omit it and you get every trim for that vehicle
• Each entry returns trim, tiresize, torque_ft_lb, fastener_type, load (load index), speed (speed rating) and xl (extra-load flag)
• torque_ft_lb: null means the figure is not published for that fitment — consult the vehicle manual. It does not mean zero and it does not mean the lookup failed. When two upstream sources disagree we deliberately withhold a number, because under-torque is the wheel-loss failure mode and a wrong figure is worse than none. Coverage is partial — about 72% of fitments as of 2026-08-22, up from 45% a week earlier — and still growing
• Check fastener_type before you label the value. It is "lug_nut" or "center_lock" (and null when the torque is null). A centre-lock hub uses a single central nut at a much higher torque, so a UI must not blanket-label the figure "lug nut torque"
• Requires a paid plan — Starter, Pro, or Business. Free keys receive 403 Paid subscription required
• No monthly quota — calls run on your plan's daily request limit only. Unlike /tire_dimensions, which counts against the monthly fitment allowance, the paid plan is the only extra requirement here
• Responses are not cached — the data is vehicle-specific, unlike the reference list endpoints

• All makes: GET /api/v1/search_allmake
• All years: GET /api/v1/search_allyear
• All widths: GET /api/v1/search_allwidth
• Year range for a make: GET /api/v1/year_range?make=Toyota

• Each plan has a daily request limit that resets at midnight Eastern Time (America/Toronto)
• Free: 300 requests/day (up to 100/hour) — a fair-use burst guard. The Free plan's headline allowance is 250 tire lookups/month; see the quota table below
• Starter: 5,000 requests/day
• Pro: 50,000 requests/day
• Business: 80,000 requests/day (custom limits available)
• When you hit the limit you receive a 429 Too Many Requests response — monitor usage from your dashboard

• Monthly endpoint quotas. Four endpoint groups carry a monthly quota in addition to your daily limit. These reset on the first of each month (America/Toronto):

• Everything else — the /by_vehicle cascade steps (make, model, trim), /by_size, /oem_specs and the reference lists — runs on the daily limit only
• Read Fair Use & Data Protection for the full picture, or call GET /api/v1/usage to see your current numbers

• Header name must be exactly x-api-key — not X-API-Key or apikey
• Check for leading or trailing spaces in the key value
• Confirm your subscription is active in your dashboard
• If you recently regenerated your key, make sure you're using the new one

• Use /search_allmake to get the exact make string — spelling matters (e.g. Land Rover not Land-Rover)
• Use /year_range?make=Toyota to confirm the year is within our dataset
• Try without the trim parameter to get all trims for that model first

• Two endpoints are gated to the Business plan: /search_allsizes and /premium/advanced-search
• /oem_specs is not Business-only — it needs any paid plan (Starter, Pro, or Business) and answers Free keys with 403 Paid subscription required, so upgrading to Starter is enough
• The response includes your currentPlan so you can confirm which plan the key is on
• On another plan, build a size list from /search_allwidth plus /by_size/aspectratio and /by_size/diameter instead
• Getting 403 Subscription expired instead? Renew from your dashboard — the response includes the expiredOn date

• These two responses mean unusual bulk-access patterns were detected on your API key, and access was restricted under Terms of Use §7.1
• 429 Access temporarily throttled clears by itself — but only once the key has actually gone quiet. Stop the bulk job. Waiting is not enough on its own: a script that keeps retrying at speed will stay throttled for as long as it runs, however many hours or days that is
• Honour the Retry-After header — it is the earliest your key can be reconsidered, not a guarantee. A client that backs off to one call an hour counts as quiet and will clear
• Each repeat throttle needs a longer quiet period than the last, and after several the key stops clearing automatically and needs a support review
• If the 429 arrives with no Retry-After header, that review point has been reached — contact support
• 403 Access suspended is reviewed by a person. Contact support to have it looked at; tell us what your integration does and we'll get you unblocked if it's legitimate
• Common innocent causes: a backfill or migration script iterating over every vehicle or size, a retry loop with no backoff, or a cron job re-fetching data you could cache
• Practical fixes: cache the reference endpoints (/search_allyear, /search_allmake, /search_allwidth) for at least a day, request data on user action rather than pre-fetching it, and add exponential backoff

• Read the error field — a 429 can come from your daily limit, your hourly limit (Free plan), a monthly endpoint quota, or a throttle
• Monthly quota: /by_vin, /reverse_lookup, and /search_allsizes each have their own monthly allowance that is separate from the daily count — check GET /api/v1/usage
• Free plan hourly cap: 100 requests per hour, resetting at the top of each hour (America/Toronto) — a fair-use burst guard, not the plan's headline allowance
• Burst protection: sending more than about a request per second from one key trips a short cooldown — spread requests out and reuse cached reference data