Speedo correction for larger tires?

No idea how much they cost but the Jeep we bought last fall had 35" tires on it and we had to put on 265's to fit on the rollers at our emissions test, and I needed snow/ice tires for the winter canyon roads. The Jeep came with a device from Superlift that use can manually adjust it easily. Haven't gotten around to bothering but something like that might be a good option if someone changed back and forth a lot and didn't want to mess with the programming.

Oh yeh, the short tires mean I can get in the garage at work which is a big plus!