Privacy policy
Datum has no accounts, no analytics, no advertising and no cookies. This page explains what still happens to data when you use it.
The short version
- You do not need an account, and no form on this site asks for your name or email address.
- The tire and wheel numbers you enter are worked out in your browser. The page does not send them anywhere.
- The company that hosts the site, Cloudflare, receives the technical details any web host receives, such as your IP address, so the site can be delivered and protected.
- If you choose a colour theme or units, your browser can remember that choice on your own device. It is saved only when you make the choice.
- Datum does not set cookies, run analytics or show advertising today. If that changes, this page will change first, and anything that needs your consent will ask before it runs.
Who runs this site
Datum is run by an independent publisher. You can contact us at supportdatum at gmail dot com. Where data protection law uses the term, the person or business named here is the “controller” of the personal data described on this page.
What you type into the calculator
Tire sizes, wheel widths, offsets and any measurements are calculated in your browser. The page does not send them to a server, and the site has no database to keep them in.
The page address updates as you edit, so you can copy a link to the same comparison. That address contains your numbers. Nothing is sent when it updates. But when a link with numbers in it is opened, whether by you or by someone you shared it with, the address is part of the web request made to the host, so those numbers can appear in the host’s logs like any other part of a web address. The copy-link button puts the address on your clipboard when you press it, and does nothing else.
What the hosting provider receives
Datum is a static website hosted on Cloudflare Pages. Whenever your browser loads a page, picture, font or script from Datum, Cloudflare receives the usual technical details of an internet request: your IP address, the address requested, the date and time, your browser and device type, your language settings, the page you came from and connection details. Cloudflare uses them to deliver the site, to keep it secure against attacks and abuse and to run its network, under its own privacy policy.
We do not run analytics on this site, and we do not receive or keep a log of individual visits.
What is saved on your device
Datum can save up to 2 small entries in your browser’s local storage, and nothing else:
| Name | What it holds | When it is saved | Why |
|---|---|---|---|
datum-theme | "light" or "dark". | Only when you press the colour theme button. | So the page uses your choice next time. |
datum-units | Your choice of inches or millimetres, and mph or km/h. | Only when you change a unit switch. | So the calculator starts in your units. |
These entries stay on your device. They are not cookies, they are not sent to us or to anyone else, and they are not used to track you. Clearing your browser’s site data removes them, or you can use the button below.
Saved on this device right now
This panel needs JavaScript to read your browser’s storage. Without it, this site has not saved anything.
Because this storage only remembers a choice you made and is used for nothing else, there is no cookie banner. Datum does not use cookies at all.
If you email us
We receive your email address and whatever you write. We use it to read and answer your message and to keep a record of the conversation. We do not add you to any list, and we delete correspondence once we no longer need it.
What we do not do
- We do not sell your personal information, and we do not share it for advertising.
- We do not build profiles of visitors or track you across other websites.
- We do not use your information to make automated decisions about you.
- Datum is not aimed at children, and we do not knowingly collect information from them.
Because we do not track visitors, signals such as “Do Not Track” and Global Privacy Control do not change anything here.
Advertising
Datum shows no advertising today. Free tools like this one are often paid for by advertising, and Datum may add it in future. Before that happens, this policy will be updated to name the advertising partners, say what they collect and why, and explain how to opt out. Where the law requires your consent, as it does in the UK and the EU, advertising cookies and similar technologies will not run until you agree, and you will be able to change your mind on every page.
Your rights
Depending on where you live, you may have the right to ask what personal information we hold about you, to have it corrected or deleted, to object to or restrict how it is used, to receive a copy of it and, if we ever rely on your consent, to withdraw it. In the UK and EU you may also complain to your data protection authority, such as the Information Commissioner’s Office in the UK. California residents have rights to know, delete and correct personal information, to opt out of its sale or sharing, and not to be treated differently for using these rights (see the California Attorney General’s summary). Residents of some other US states have similar rights.
Because Datum holds almost no personal information, a request will usually find that we hold nothing except any emails you sent us. To make a request, write to supportdatum at gmail dot com. We may need to confirm that you are the person concerned, and we will reply within the time the law allows, usually one month in the UK and EU and 45 days in California.
Legal bases
Where UK or EU data protection law applies, we rely on legitimate interests for the technical data our host receives (delivering and securing the website) and for answering your emails, or on taking steps at your request. Nothing optional runs on this site without your consent.
Where data goes
Cloudflare runs a global network, so technical data may be processed in countries other than yours, including the United States. Cloudflare describes the safeguards it uses in its own privacy policy and data protection documentation.
Security
The site is served over HTTPS only. It has no accounts, no database and no user-generated content to protect, and it uses security headers that restrict what the pages may load.
Changes to this policy
When something changes, we update this page and the date at the top. If a change affects what you have been told about advertising or tracking, it will take effect only after the new text is published here.
Contact
Privacy questions: supportdatum at gmail dot com. See also the terms of use and accuracy and limits.