Anyone know roughly what a typical spring rate is for a street tire? Hoosier publishes this information, but I've yet to see any data for street tires.

 

Why don't you measure it?
Jack up one end of a car and slowly lower it until the tire just barely touches the ground. Measure the distance from rim to ground.
Then lower the car all the way and measure again.

Depending on tire PSI, the rim will be about 1/2" lower, and the weight of that corner is about 500 lbs, so maybe 1000lbs per in? Which sounds like a typical number. The spring rate is probably non-linear, since the tire is easy to deform initially and gets harder the more you compress it. Thus take the number you measured, and increase it a bit to guess at the incremental static spring rate, or whatever it's called.

A wider tire will probably have a higher spring rate, and a street tire with soft sidewalls will be lower.

BTW, I just made all of this up right now.

 

What is your intended use for this information?