HUD for Inaccurate Analog Speedometer

My 18 y/o’s Tundra has Nitto 35x12.5x20 tires that has the SR5 analog speedometer reading 3-4 mph lower @ 60mph. No surprise that the offset gets larger the faster the speed. Really don’t need him getting any speeding tickets. While experimenting with an iPhone app (Commander Compass) with a Bad Elf aviation GPS dongle to get better GPS mph readings, it was interesting how far off the GPS speed readout can be at times on the factory NAV screen on Waze, so was looking for a solution since currently we can’t get a tire size correction from Toyota. Miss th e old days on Toyota’s where you could change out the Speedo gear on their trannys.
Found a cheap option. I chose a OBD HUD system, and used the Acecar version on Amazon for around $30. The unit has all kinds of display options in the setup mode, but I just wanted the simple speedometer function. It can use its internal GPS for speed if powering by USB, or I went with their option of using the OBDII port that feeds the vehicles speed output, and also powers the unit. Took a few tries to set up all of the parameters. I used the optional windshield reflector (looks like mirror windshield tint) and found the display works well in daylight, and the parameter for auto dimming did well for nighttime use. Ran OBDII connection off the HUD between windshield & dash, then went behind A-pillar weatherstrip, and into dash where it plugs into the OBDII port, so no wires are exposed.