It's definitely possible that this happens, but I doubt that a lot of people would go out of their way to have that kind of setup. If you have the tools, the willingness to change tires, and the space to hold on to 4 spare ones, I feel like you're probably also not the type to run tires bald and risk an accident just for ~$450 a year.
(amount is from the rough average annual mileage of 13,500mi/year, assuming 30mpg, and the 82c/gallon tax).
Sounds like you'd pay for the tires (which then last forever, since you aren't driving on them) in just one year. Maybe two if you drive a truck. Lots of people have wrenches and spare garage space. And plenty more are already dumb enough to drive on bald tires. Let's not make this worse.
Incentivizing the failure to replace wear items is bad policy.
Tires have a born on date stamped on them and they also crack and wear with age even if they're not used unless you seal them up. I think you're overestimating how many people would be willing to do the swap and consciously ride on bald tires, but I can concede that I might be wrong on this. CA could run their own investigation if they so choose to.
> Incentivizing the failure to replace wear items is bad policy.
I see it as the least bad option out of the ones that we can field. Every kind of taxation policy will have pros and cons, and IMO the tire tax is potentially the one with the least amount of friction to implement and enforce.
(amount is from the rough average annual mileage of 13,500mi/year, assuming 30mpg, and the 82c/gallon tax).