Is the VIN really not sent anywhere?
Yes, and you can check it rather than believe it. Open your browser's network panel before you press Decode: the only request is the vehicle database, it happens before the VIN is read, and it is the same file for every visitor. There is no address on this site that accepts a VIN, so there is nothing for one to be sent to. Turn the network off after the first decode and the second one still works.
Why does decoding in the browser matter?
A VIN identifies one specific vehicle, and a seventeen-character string that names your car is worth something to whoever collects it. Every other free VIN lookup sends it to a server, because querying a database over a network is the only architecture available to them. The database here is public and small enough to carry, so the transmission is not a trade-off we accept. It does not happen.
What does a VIN number lookup here tell me?
Make, model, model year, body class, engine cylinders and displacement, transmission, drive type, the plant that built it and everything else NHTSA's pattern database records for that VIN — typically twenty to thirty fields. It is the same data every free decoder returns, because it is the same government source.
What does it not tell me?
Nothing about this particular car's life: no mileage, no owners, no accident, title or salvage history, and no window sticker. Those are not in the pattern database and never will be. Accident and title history reaches consumers only through commercial providers approved under NMVTIS, which publishes no public interface, so every free offer of one is a route to a paid report.
Why does the first decode take a moment?
It downloads about four megabytes: NHTSA's vehicle pattern database, compressed. That happens once. Your browser keeps it, so every later decode — on this visit or any other — is arithmetic against a file already on your device, and needs no network at all.
Do you spell it tire or tyre?
Tire, throughout. The data behind this site is United States federal data, the audience is a US-market car buyer, and the calculator is the one they will search for by that spelling. If you arrived looking for a tyre size calculator, it is the same page.