# Riveted at the last flat surface before you shut the door > A tyre pressure plate is riveted where it is because that's the last flat surface you see before shutting the door — four figures placed exactly where you'll need them. August 19, 2026 · https://justog.club/stories/tyre-pressure-door-plate A small metal plate, riveted flat. TYRE PRESSURES across the top, a table beneath it — front and rear, normal and laden — and two words at the foot: CHECK COLD. Those two words are quietly cancelling half the reason the plate exists. ## What is this plate actually telling a driver? The correct pressure for the front and rear tyres, and that it changes with how loaded the car is. FRONT reads 32 unladen and 36 laden, REAR reads 30 and 38. Two states, not one — a car carrying passengers and luggage needs firmer tyres than one running with a driver alone, because the extra weight needs more air pressure to be supported without the sidewall flexing more than it should. ## Why is the plate riveted inside the door rather than on the tyre itself? Because that's the last flat surface a driver sees before shutting the door and driving away. A tyre's own sidewall carries a maximum pressure figure, not the running figure for this specific car, and reading it means crouching at the wheel with a torch. The door plate sits at eye height, at the one moment in the whole day when a driver is already standing right there — which is the entire idea behind putting a reference figure there at all: put it where the person will be anyway. ## Why does CHECK COLD matter enough to be printed on the plate itself? Because a warm tyre reads a higher pressure than the same tyre actually is. Air expands as it heats, and a short run on a motorway heats the air inside a tyre enough to shift the gauge reading upward, without the tyre actually holding more usable pressure once it cools back down. A figure checked hot looks fine and is quietly wrong, which is a worse failure than an obviously low reading — CHECK COLD is the plate correcting for that in advance. ## Can a real carmaker's plate design go on a shirt? A specific manufacturer's plate — its layout, its badge, its model name — belongs to them and is licensable the ordinary way. The figures themselves aren't anybody's: a pressure recommended for a given tyre and load is a fact about physics, not a trademark, which is what lets a plate be redrawn from scratch and still be entirely accurate to how the real thing works. ## Does the same format work for something other than tyres? Anywhere a number is only correct under one specific condition and wrong under every other one it looks similar to. A tank gauge that reads differently on a slope, a scale that needs taring before each weighing, an instrument that has to warm up before it's trusted — all of them carry the same quiet second line a tyre plate carries, telling the reader what state the reading has to be in before it means anything. [A valve clearance table does the same thing from the other direction](/stories/valve-clearance-table), giving a figure and then naming the one condition it has to be measured under. ## Isn't checking tyre pressure obsolete now dashboards flag it automatically? A warning light says a tyre is already low. It doesn't say what the correct figure was supposed to be in the first place. A sensor tells a driver something's wrong after the fact; the plate is what lets anyone put the right number back in, for this car specifically, at this load — which is also [the same job a warning lamp key does from inside the cabin](/stories/handbook-warning-lamp-key): one flags the problem, the other supplies the fix. ## Does it print well? Yes — a small riveted plate with a tight table is exactly the kind of artwork that survives fabric well. Keep the table hard-edged and the rivets as simple circles rather than shaded discs, white for the structure and yellow reserved for CHECK COLD, so the instruction stays the one thing that stands apart from the numbers. Charcoal or steel grey keeps it reading as metal. ## How do I get one made? Describe your plate at [JustOG](/) — the figures front and rear, laden and unladen, and the line underneath. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to order and shipped. Designs other people have published are in the [shop](/shop). Four numbers, correct for exactly one condition, checked at exactly one temperature.