Tire Aspect Ratio and Rolling resistance
Generally lower aspect ratios are likely to be advantageous for rolling resistance. If the construction and materials are identical, a 60-series tire has less rolling resistance than a 70-series by about 5%.
From an article on a govt site.
This report examines the current and expected future trends in highway tire design and their effects on vehicle rolling resistance and fuel economy.^The primary emphasis is on passenger cars, operated under conditions typified by the US Environmental Protection Agency Urban, Highway, and Combined Cycles, and heavy duty trucks operated over the road.^Analytical and experimental data indicate rolling resistance-fuel economy sensitivity factors of 0.2 for passenger cars over the Combined Cycle, and 0.4 for a fully loaded tractor-van trailer at 55 mph.^Improved radial construction, low hysteresis materials, and higher inflation pressures are the primary mechanisms through which passenger car tire rolling resistance has been reduced.^Further design refinements are expected in the near future to achieve reduced rolling resistance and optimal ride and handling qualities at acceptable production cost.^Similarly, heavy duty truck tire designs have been improved through the use of radial construction, and further rolling resistance reduction is expected through design modifications such as lower aspect ratio.
It seems like a tradeoff between load and Crr. Bicycle tires have so little aspect ratio they can't even hydroplane and excellent, CRR. However they also can't carry much very fast.
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
high profile is mainly for comfort versus performance. A lower sidewall gives you a more quick response due to less flex from said sidewall. Lower profile tires require larger diameter rims to compensate, increasing weight (unless you get lightweight rims) and leads to more curb rash on rims due to a combo of less rim edge to ground clearance and harsh road conditions or unskilled maneuvering around your local Wal-mart, chatting up a friend on your cell and not looking out for the 6" raised concrete apex you just nailed (saw this last week). I assume the tire selection on hybrids has to due w/ them primarily being used as family transportation and not autobahn demons. Low profile sacrifices comfort and soccer moms and dads can't have that. Not offense to soccer or ppl w/ kids. Mak
'85 CRX Si Original EW3 @ 254k...suck it Detroit
'89 CRX HF-Z1 ~ When haste is needed
'97 Civic DX Hatch ~ Formerly 600hp, now 0hp, soon 115hp.