key finding.. 19" RFT specifically are the issue not RFT in general

[CedarZ4]

Ah, I see. So what you are saying is, the flex in the tire around a turn resulting in part of the sidewall being in contact with the road creates that larger contact patch, therefore resulting in a grippier feel?

[HerrK]

Originally Posted by CedarZ4

Ah, I see. So what you are saying is, the flex in the tire around a turn resulting in part of the sidewall being in contact with the road creates that larger contact patch, therefore resulting in a grippier feel?

Not exactly anticipating much contact patch improvement from the sidewall. The RFT's are more like tilting a box up slowly or to exagerate tilting it up until you only have only the corner edge in contact.

On the other hand, the NRFT's will roll in the lateral direction of travel, during coner loading, around the beed, and change sidewall shape to mantain mechanical grip with the tread over a corresponding larger contact patch (relative to the RFT).

Here's another visual. One day while at Costco I was wasteing time waiting for tires to be installed on my wifes car. Came across a set of 19" BS RE050A's RFT's. Took one off the pile and layed it flat on the gound (as in on the sidewall), now the tire is unmounted and obvioulsy not inflated. Next I stand on the sidewall at the beed, all 150lbs of me resulted in less than 1/4" deflection. Tried that with a similar sized NRFT and get about 1-1/2" deflection.

And this is why tire pressure is considered, finely tuned, and adjusted during almost all forms of motor racing. To maintain, improve or remove the size of the contact patch during cornering - depending on if a car is over or understeering. Obvioulsy they also adjust the suspension but the air pressure is a part of the equation.

With RFT who cares about tire pressure. They are designed to Run Flat with only minor compromise in driving style is a straight line or around a curve.

[nicknaz]

That's a bit of blanket statement on the rft side wall roll,no?

I've scuffed 17" rft sidewall on track as much as non rft.

19 re050a with 30 series sidewall I think are a special case because they can't allow much if any roll or the wheel will hit the track.

Agreed with cedar that it is more about compound choice than rft or not