[homer09]

Originally Posted by flatthump

Question about Tire pressure and Spring rates Stretch.

I was at a meet and this "suspension engineer" was trying to tell me that every 2psi is the equivalent to 10 more pounds of spring. He actually said "spring rate"

What are your thought on this. I figured the more air psi in the tire, the more energy the spring/shock has to absorb. Leading to mre stroke being used. Which is the opposite of what higher spring rates do.

he was most likely talking about total wheel rate, which includes the tire's spring rate.

[flatthump]

Originally Posted by homer09

he was most likely talking about total wheel rate, which includes the tire's spring rate.

Thats what I though. But most engineers like to use technical language. He said "Spring rate". So I was interested.

[homer09]

Originally Posted by flatthump

Thats what I though. But most engineers like to use technical language. He said "Spring rate". So I was interested.

well in most engineering books they will use the words "spring rate" for everything (coils, tires, swaybars, etc). simply because everything is modelled as a spring and damper system. therefore, spring rate is the logical word choice, and it is not limited to actual suspension coil springs.

[flatthump]

Oh. I learn something everyday here.

But I could have sworn, in the last book I read, "Brilliant Suspension", They used the words "Corner rate" when discussing these things. So as not to confuse the reader I guess. So I dont think everybody uses the word "spring rates" when explaining issues like this.

[stretch]

Tires are very complex. The spring rates of a tire aren't even close to linear, so it's hard to generalize them with a "rule". They do have a spring rate, though, for sure.

Edit: I've attached a graph of a 225/45/17 tire @ modeled at 36psi. These are calculated estimates, not actual data.

[flatthump]

Well ya.....for every unit compressed (tire compressing), the air-pressure for the following interval raises much more that the tire compressing. It may even be an exponential function.