Privacy policy
Last updated: October 24, 2026
Short version: the numbers you type into our tools stay in your browser. No accounts, and no cookies of our own. Google AdSense, which shows ads on the site, sets cookies (see "Analytics and ads").
Who is responsible
Rainer Lang
Dalkinger Straße 27
73479 Ellwangen
Germany
Email: info@checkfitment.com
What the tools do with your numbers
The calculators (bolt pattern, offset, backspacing, spacers, plus sizing, speedometer, gear ratio and the others) run in your browser. The wheel widths, offsets, tire sizes and ratios you enter are not sent to us or to anyone else, and the site stores nothing about them on your device. Some tools can be filled in from the web address, for example when you follow a link from a vehicle page; that also happens in your browser. The vehicle specifications come from the site's own dataset.
Hosting
The site is hosted by Cloudflare, Inc. (Cloudflare Pages). To deliver the pages, Cloudflare processes technical data such as your IP address and browser type, as any web server must. The legal basis is our legitimate interest in running a secure, working website (Art. 6(1)(f) GDPR). Cloudflare's privacy policy: cloudflare.com/privacypolicy.
Analytics and ads
The site uses Ahrefs Web Analytics. It sets no cookies and does not track you across other sites.
The site shows ads served by Google AdSense (publisher ID pub-9037079666892173). Google and its advertising partners (vendors) use cookies and similar identifiers to serve and measure ads and, where you have consented, to personalise them. Google may use the information from your visit to this and other sites: how Google uses data from sites that use its services. Visitors from the EEA, the UK and Switzerland are asked for consent through a consent banner before ad cookies are used; the legal basis is your consent (Art. 6(1)(a) GDPR), which you can withdraw at any time through the banner's privacy settings link. You can opt out of personalised ads at adssettings.google.com or aboutads.info. Ads never influence which numbers our tools show.
The site contains disclosed affiliate links (WheelXL via Awin): if you click one, Awin and WheelXL set their own cookies on their sites to credit the referral. CheckFitment sets no cookies itself; Google's ad cookies are described above.
What the AI assistant apps send us
If you use CheckFitment inside ChatGPT, Claude or another AI assistant (for Google Sheets, see the next section) that connects to our MCP server (see CheckFitment for AI assistants), the assistant sends our server only what the tools need for the answer: the vehicle make, model and year you ask about, wheel widths and offsets, tire sizes, spacer thickness, gear ratios or a bolt pattern. The app does not ask for names, addresses, VINs, license plates or your chat history, and you should not enter them. Our code does not store or log what it receives; the answer is computed from the site's dataset and returned. Cloudflare, our host, processes technical data such as your IP address to deliver the request, as described under "Hosting". Your conversation is processed by the assistant's provider under its own privacy policy (for ChatGPT OpenAI, for Claude Anthropic). The apps set no cookies and show no ads.
Google Sheets add-on and Google user data (Limited Use)
If you use the CheckFitment add-on in Google Sheets, the add-on sends our server only what you type into its sidebar form: vehicle make, model and year, tire sizes, wheel offsets, spacer thickness or an axle ratio. Our code does not store or log it; Cloudflare, our host, processes technical data such as your IP address to deliver the request (see "Hosting"). The add-on sets no cookies and shows no ads.
Google user data and Limited Use. The add-on does not read, copy, store or share the contents of your spreadsheets, your files, your contacts or any other Google account data. Its only access to your spreadsheet is writing the result rows you ask for ("Insert into sheet") at the cell you have selected; it uses the position of that cell, never its content. CheckFitment's use of information received from Google APIs will adhere to the Google API Services User Data Policy, including the Limited Use requirements. We do not use such data to develop, improve or train generalized AI or machine-learning models, we do not transfer it to third parties, we do not sell it, and no human reads it.
If you email us, we use your address and message only to answer you, and delete them when they are no longer needed for that.
Your rights
Under the GDPR you have the right to access, correct, delete or restrict processing of your personal data, to object to processing, and to complain to a data protection authority. Write to the email address above.
Last updated: October 24, 2026.