They’ll still have to replace them more often or won’t be able to drive their vehicles or pass a state inspection to get their annual registration completed unless their car is road-worthy, thus costing them more money in tickets and remedies of said ticket.
Sure, but the problem is that you dont want to make safety equipment more expensive, as it encourages cheaping out and cutting corners. People already buy cheap and nasty tires that dont grip well or stop well (but still meet roadworthiness), its best to avoid further encouraging that.
There is no reason not to just directly tax against the weight of the car, as defined by the manufacturer. There already is a yearly rego payments, just scale that directly against weight.
A direct tax is also clear and obvious. If someone has a large car, the rego weight tax will clearly show they are paying more. Making tires more expensive just gets rolled into the price of the tire, which are already moderately expensive, so its easier to just rationalise it and ignore it.