transamz9 wrote:
The stiffer sidewalls they are referring too are short sidewall (like on mine and your Corvettes) or higher rated tires (air pressure)
That's your opinion, not their statement. They never said with a tall sidewall, the rule does not apply.
A NASCAR generates over 2g of side force, with a very tall profile, at only 30psi. They maintain fairly square contact patch. Try it on your typical P rated tire and see just how much you'd roll into the sidewall. I have auto-crossed with 225/60/16 tires at 47psi, and I am still rolling heavily into the sidewall.
The very short sidewalls on the tires they are talking about are very very sensitive to air pressure change because of the very light weight cars they are being run on and also the fact that there is very little air volume to cushion the bumps and allow for the sidewall flex that some people are looking for.
Quite the contrary. Short sidewalls makes tires INSENSITIVE, because the sidewall contributes much more to vertical and lateral loads. Again, think about the F1 EMT tires, it runs perfect at 30 psi, and still works marginally at 0 psi. We can extrapolate and say at 15 psi it works somewhere in between.
A 265/75 tire works perfectly at 30 psi, is about to loose a bead at 5 psi, and does not work at all at 0 psi. We can extrapolate and say at 15 psi it's only marginal.
Again, if sidewall stiffness doesn't matter, the truck tire shouldn't fall off the beat when the EMT can drive around safely.
Read the side wall on you Vette tires and the sidewall on you truck tires. Side wall ply is 2 Polyester. The higher load rated tire will be stiffer when air to is max but when aired to the same as the same size lower rated tire it will flex the same.
Then by your statement, runflats would never work, because at 0 psi, it HAS to behave, and ride, and handle, like any other tire at 0 psi.
So why is it that the EMT still rides like a buckboard at 0 psi, and therefore 5 psi, whereas a normal tire at 5 psi would ride balloon soft?
BTW, there's more to a tire's construction than just the number of plys. The thickness of the rubber (and belts) and its compound contributes heavily to a tire's carcass stiffness.
If he don't increase the air than the sidewall is going to flex the same. The compound of the tire is what going to determine how quick it wears out if he doesn't overload the tire.
Then why is he looking high and low for a "stiff tire", to protect his rim? If tires of all construction are the same stiffness, then "stiff tire" won't even be a phrase. Why doesn't he simply pump up the tire?
Read further in the thread:
"The stiffest tires you can get are the run flats (RFT). They cost quite a bit and don't absorb the shocks a lot either though."
Why is the RFT stiffer? Do owners pump more psi when using a FFT? No. Therefore the sidewall must be contributing to the stiffness.
"I just went from Pilot PS2 AS to Conti DWS for my "all season" tires.. cant stand the sidewall flex"
Again, did he lower the pressure upon mounting All Seasons? No. Likely his pressure remained the same, and is complaining because the soft sidewall ruined the handling.
To get a stiffer sidewall you have to increase the air pressure or lower the air volume. So you will have to go to a heavier load rated tire to be able to increase the air pressure or get bigger rims and go to a shorter sidewall but then you will have to go with bigger wheels to keep the height.
Increasing the air pressure or lowering the air volume makes SAME tire stiffer. But you can make a tire stiffer at the SAME pressure and air volume. Again, if this wasn't true runflats won't work.
