I'm so tired of this moron...
Here's a great way for anyone here to see for themselves that Wilson is an idiot, spewing his "theoretical physics". Welcome to the world of applied
This is my favorite way of checking contact patch. Yeah, it's not perfect, but it's quick and accurate. Get a piece of cardboard, jack the vehicle up, and put it under the wheel. Set it down (slowly, no squish factor needed here), and let it sit for a minute. The tread will compress the cardboard where it makes contact. Since the cardboard is one 1/8" thick, there's not much deformation, but there's enough to accurately see what your contact area is. You don't have to take my word for it, and we all know that 10 hours later Wilson will come back with some BS "theoretical" explanation for why it's wrong based on something he finally found on Wikipedia, or tell me I cheated and changed the tire pressure, or whatever else nonsense he can come up with to support his obviously incorrect stance he has dug himself so deep into there is no graceful way out of.
So don't take my word for it, feel free to try it yourself. Seriously, it only takes about 20 minutes. Here's what I did yesterday. 3 tires: a 125/90-16 (factory XJ spare, don't know how wide the wheel is), a 31-10.50-15 Duratrac on a 15x8, and a 33-12.50-15 KM2 on a 15x8, all set at 38 PSI, all on a 4 door XJ.
And here's the big one:
And your summary, and for the math-challenged Wilson, the area already calculated for you. (some slight rounding, but you can see the tape measure in the pictures before this)
The 33x12.50 measured about 6.5"x8.75", or about 56.9 in^2
The 31x10.50 measured about 6.25"x7.75", or about 48.4 in^2
And the spare 125/90 measured about 6.25"x3.5", or about 21.9in^2
How can this be? Same weight vehicle, same air pressure in the tires? It's because tires are not balloons, they are rigid, and have physical constraints, which does
include the rim width btw.
Now, what Wilson is really talking about is contact pressure
. A 4500lb object with 100in^2 of contact area will exert a pressure of 45 psi on the ground. That doesn't mean there's 45 psi in the tires (it doesn't mean there isn't 45 psi in them either, it's irrelevant).