I have been considering buying a hybrid vehicle, now look what Ohio and other states

[Salviati]

17. Yup, learned that back in a history of industrialization class back in college and it's stuck around

I should a have been a bit more clear, the rule I had been referencing is that it's proportional to the fourth power of axle weight, so more axles would tend to reduce the wear...

You can find it on Wikipedia, along with their sourcing
https://en.wikipedia.org/wiki/Gross_axle_weight_rating

and a bit of talk about the determination of this at this page - where it goes into the orgins of this rule in a report put out by the highway engineers at The American Association of State Highway Officials, in the 50's and 60's, where they ran emperical tests to measure road wear.

http://www.cyclelicio.us/2014/fourth-power-rule-road-tax/

The exact conditions and measure of wear can play a big role in that however. A more recent paper, from the Texas Dept of Transportation in 2001, that looks at differences between more flexible and more rigid pavement, as well as different measures of wear - cracking vs. rutting, shows that the exponent can go down for some measures, e.g. the rate of cracking goes like axle weight squared, but rutting like axle weight to the 8th power.

https://ctr.utexas.edu/wp-content/uploads/pubs/2122_1.pdf

So, as is to be expected, real world data is messy, but what does seem to hold up is that road wear increases very rapidly with vehicle (axle) weight