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aerohead · 12-05-2009, 03:33 PM

I caught this thread but am away from home and library.I'll throw out some things,hope they're correct,verify once back home,and be back.
Many of the low-drag high mpg concept cars incorporated narrow,large diameter,elliptical,low aspect ratio,high-pressure radials,with tread designs which had all individual tread blocks,designed for low squirm,and total absence of "quiet-bands" which,while reducing tire noise,do so at the expense of higher drag.These tires were compounded for high-hysteresis and may have traded low-R-R for both dry and wet traction.Some of these tires were also designed for run-flat capability which would allow the automaker to delete the spare tire as a weight-saving technique for better urban mpg.
The FORD Probe-IV had 155 size tires specifically to reduce aerodynamic drag by virtue of their 10% reduced frontal area,compared to conventional radials of that period.
Many reports on the development of particular vehicles will sight the variance in Cd as a function of tire width.There is a definite correlation,there has to be,as drag is an arithmetic function of CdA.
And while I believe modders are more attuned to the safety ramifications of diverging from O.E.M.spec equipment and will attempt to compensate with driving style and technique,the automaker must design for those compelled to have their Darwinian moment.
I consider my own driving to be very conservative and I don't consciously desire to pose a threat to myself or innocents around me,and strive not to be "blinded" by mpg "euphoria"and inadvertantly do something really stupid and dangerous in the name of better mpg.
Always think safety.

12-05-2009, 03:33 PM	#19 (permalink)
aerohead Master EcoModder Join Date: Jan 2008 Location: Sanger,Texas,U.S.A. Posts: 16,267 Thanks: 24,392 Thanked 7,360 Times in 4,760 Posts	narrow I caught this thread but am away from home and library.I'll throw out some things,hope they're correct,verify once back home,and be back. Many of the low-drag high mpg concept cars incorporated narrow,large diameter,elliptical,low aspect ratio,high-pressure radials,with tread designs which had all individual tread blocks,designed for low squirm,and total absence of "quiet-bands" which,while reducing tire noise,do so at the expense of higher drag.These tires were compounded for high-hysteresis and may have traded low-R-R for both dry and wet traction.Some of these tires were also designed for run-flat capability which would allow the automaker to delete the spare tire as a weight-saving technique for better urban mpg. The FORD Probe-IV had 155 size tires specifically to reduce aerodynamic drag by virtue of their 10% reduced frontal area,compared to conventional radials of that period. Many reports on the development of particular vehicles will sight the variance in Cd as a function of tire width.There is a definite correlation,there has to be,as drag is an arithmetic function of CdA. And while I believe modders are more attuned to the safety ramifications of diverging from O.E.M.spec equipment and will attempt to compensate with driving style and technique,the automaker must design for those compelled to have their Darwinian moment. I consider my own driving to be very conservative and I don't consciously desire to pose a threat to myself or innocents around me,and strive not to be "blinded" by mpg "euphoria"and inadvertantly do something really stupid and dangerous in the name of better mpg. Always think safety.