However, whatever paint colour is applied to the custom wheels will also be applied to the stock spare. If the player customizes the vehicle by changing the wheels, the spare 'stock rim' will remain unchanged. The Merryweather Mesa has a spare wheel mounted on rear. That segment seems designed to be played by entering through the front door, not the garage.)
If it does open, then Michael would have a second access route into his house, which might spoil the 'saving Amanda' portion of the mission. Personally, I haven't tried this option, and I don't know if Michael's garage door will open during this mission. (Also, it might be possible to save a Merryweather Mesa during the ' Meltdown' mission, which takes place at Michael's home.