B.B. u> wrote in article
>...
> In article <01c7f150$8e8f9280$f192c3d8@race>,
> "*" > wrote:
>
> [...]
>
> > Now, could you please answer the rest of the questions I asked?
> >
> > I'm REALLY curious about the part where you say, "I've been farting
around
> > with tires for 30 years, and using different sizes for different
effects
> > for 20."
> >
> > As I asked before, exactly what sort of "effects" have you
> > experienced/observed using different tire sizes?
> >
> > And, I repeat......
> >
> > Since "....farting around...." with tires for 30 years has given you so
> > much insight and technical knowledge, please.......
> >
> > Tell me about your tire's actual footprint at different inflations.
> >
> > Tell me about your tire's spring rate at different inflations.
> >
> > Tell me about your tire's sidewall stiffness ratings.
> >
> > Can't do it without a tire dyno, and I seriously doubt if you have
> > one.....and, your daily tire kick doesn't even come close.
>


My original question was directed towards his claim, "I've been farting
around with tires for 30 years, and using different sizes for different
effects for 20. "

What, exactly, did he discover?

And, what tells him that he is right?


> How much does any of that matter in a passenger car? Really, I can
> understand worry over those stats with a race car since they tend to
> push the limits, but in an econo?

Just wanted to see if he actually learned anything or was simply blowing
smoke.....I'm betting on the smoke.....


> FWIW, running a tire at a higher pressure will reduce contact area as
> you have stated over and over, but it will also increase ground
> pressure. I have seen nothing from you addressing the tradeoff--only an
> assertion that less area means less traction. And with some conditions,
> such as water on the road, higher ground pressure is far more valuable
> than contact area.

I wasn't speaking about rain tires or snow tires.

That's not the condition under which the tire is used most.

As far as I knew, we were discussing dry road, and had not even considered
the complexities of less-than-ideal road surfaces.

THAT's a whole 'nuther issue.

Overinflation lifts the outside edges of the tire, effectively lengthening
the contact patch by changing the length/width ratio of the contact patch.

A wider, shorter contact patch (at the same inflation pressure) produces
more grip because less of the contact patch is slipping at the same load
and slip angle.


> As long as there is enough pressure to keep the side wall from
> bulging excessively and the tire isn't grossly above the max pressure
> printed on it, just about any pressure will do.


Only if you believe that 12.5 square-inches of contact patch on the ground
will control the car as well as 20 square-inches,

But, what if it is below the maximum pressure, but so overinflated for the
load that the outer edges of the tread are picking up off the ground?

I put load cells on my tire dyno, and you can actually SEE the loads on the
outer edges of the tread decrease as we over-inflate the tire.

On some steel-belted radials, you can see the outer edges GAIN in load as
the tread wraps around the edges of the belt upon over-inflation.


> But running low (as
> most people do since they don't ever look at their tires until one goes
> flat) accelerates tire wear.

I agree....

> He's not talking about race cars, so tire spring rate, sidewall
> stiffness, and fancy tire dynos are irrelevant. A pressure gauge and
> some eyeballs are sufficient.
>

No, but he's talking some bull about having learned things by experimenting
with the tires.

Just calling him on his over-inflated (pun intended) bluff............


Gotta' go. My 1:30 appointment just pulled into the yard.