2010 Toyota Highlander Owners Manual - Page 532

5-2. Steps to take in an emergency ● If a window tint that affects the radio wave signals is installed. ● If there is a lot of snow or ice on the vehicle, in particular around the wheels or wheel housings. ● If non-genuine Toyota wheels are used. (Even if you use Toyota wheels, the tire pressure warning system may not work properly with some types of tires.) ● If tire chains are used. Vehicles without compact spare tire ● If the spare tire is in a location subject to poor radio wave signal reception. ● If a large metallic object which can interfere with signal reception is put in the luggage room.