A couple of issues.Expected tire longevity can (and should be) a parameter in the tire's tax rate. It's just a simple issue of "expected road wear for the tire over the course of its lifespan, at its design loads".
Someone with an alignment problem will pay more.
Cars and light trucks are most often driven with less than GVW. Tires are usually spaced to be more than GVW (or at a minimum the same as GVW).
I don't see how anyone could consider this a fair tax.