Quote:
Originally Posted by Jim Allen
Capri: Is that,
"Interesting, that's the dumbest thing I've ever seen!"
or
"Interesting, cool way to do it!" ( : < )
|
Actually, my reaction was "I wouldn't have thought anyone would do it that way, even though that's a pretty good way to do it."
Quote:
Originally Posted by Jim Allen
..........
Either way, it's not my idea. It's how the programmer wanted you to find the circumference. Easy to do. I though it was cool. My other method is to measure the loaded radius with the tire inflated to the pressure I will use.
|
No!! The loaded radius is not the way to do this. BTW, this is called the Static Loaded Radius and it only affects ride height - which is why some find it a useful statistic to have.
Long story, but the short version is that the axle is off center both from the top and the bottom of the tire. The tire kind of hangs from the top and pushes down on the bottom.
Quote:
Originally Posted by Jim Allen
..........
If you have other methods, would love to hear about them!
As to centrifugal forces, a tire engineer told me regarding one particular tire (a big, high profile, 38 inch diameter, 15 inch rim, mudder) that the tire grew in circumference by several mm at high speed (he did not define "high"). I never did get to question him further to see if this was a general phenomenon, or something found just on that tire, or others like it. That's why I asked you about it.
|
This is probably a bias ply tire - and yes, those types of tires will grow. You can see this phenomenon in drag racing - especially Top Fuel where the speeds are high and the tires are exposed.
But we are talking about radial tires with a belt which restricts the growth. In fact, growth of this nature is such a problem for radial tires that higher speed rated tires will have a circumferential overlay which further restricts the growth.