I don't know what the result was 2 years ago, but it probably will be the same this year. The physics of tire design hasn't changed drastically in the last 2 years that I know of. Truck tires are higher pressure and have stiffer sidewalls to deal with the high loads they endure, not so they can get a much higher mile per gallon rating than you are permitted in your vehicle; there is no conspiracy out there denying you high pressure tires for your car.

I guess you are talking about the rolling resistance of a tire that deflects due to the weight of the vehicle? Yes, some momentum is lost as the tire flexes and that friction is converted to heat; yes a vehicle with a flat or low tire is much tougher to push; and yes a car with tires rated to higher pressure fitted onto a car and pressurized higher might be easier to push by hand and therefore use less energy to drive with the engine.

And for why not? I am not an expert in tire design, but I do know tires are designed to deflect to a certain degree for traction and stability reasons. If you want a tire with the lowest rolling resistance, take the train. Ride on a railroad designed to be smooth enough that potholes and imperfections the surface will not destroy your tires.

Ride in a car with very stiff sidewall tires that are designed for high performance and describe the difference from your average tire design. Then put that performance car on a road in poor condition and see how it holds up.

Most tires are a compromise of traction, durability and efficiency...and it is experts that know much more than I do who make that compromise. Ultimately the benefits are not as large as you probably think they are.

The road-holding of a car is strongly affected by the size of the tire contact patch. Larger contact patch = better road-holding. Lower pressure means a larger contact patch. Perhaps you have seen the very low pressure tires used on dragsters.

A tire is a compromise between rolling resistance, (which is affected by more things than just tire pressure) braking traction, cornering traction, wet traction, ice traction, loose surface traction, quietness, road feedback, and ride. The tread compounds that lead to low rolling resistance tend to provide poor handling.

The reduction in fuel consumption, in going from average rolling resistance tires to low rolling resistance tires, is not as drastic as you seem to think. But every bit helps, in certain market segments. The tires on the Toyota Prius were designed specifically with low rolling resistance in mind. Many owners do not like them for other reasons: notably rapid wear and poor handling.

But in a general sense, tires have become higher pressure in the interests of lower rolling resistance. 51 psi tires are not uncommon.

Only if your poor tired butt can stand the hard ride.

more the high tire pressure less the comfort-ride......plus, the high pressure tends to make tires with low grip-at-road profile rather than the low pr ones...a severe deterioration will occure with high pr tires due to the impacts forces on roads travel easily through the rock-like tires to the suspension system which its life reduced accordingly. As you said, a newer design of the suspension stuff could help over come this prob. means, enforce the joints , suspension, materials,,,etc to absorbe the road disturbances and damp them down before they travelled to the car body

High pressure tires have a very small "footprint" in contact with the pavement. This reduces traction. I know a guy who put 10 ply trailer tires on his light duty truck(they hold 110psi) and he skidded each time he used the brake. The lower the pressure, the more traction(to a point around 12psi) and also the less responsiveness to steering controls. Passenger cars and pickups don't have the weight to build a large enough footprint with high pressure tires. If busses were below 4000lbs, they would have 32psi tires as well.

You don't have to do that now, there are tires being made that already have low rolling resistance and more will be coming along soon. They run about 5 psi higher than oem tires but have the same traction characteristics.

Just Google: Low Rolling Resistance Tires

Detroit car makers are finally getting the message about fuel economy, both from buyers and the Federal Gov. so we should be seeing the auto support industries (except Big Oil) coming out with things to help fuel economy.

interesting. I would address the 'bumpy' ride by adding suspensions to the seat etc. to save our 'tired butts', or a better suspension to address the automobile components.

Any numbers on how much mileage we would get with a higher pressure?

Would you think of having your tires economically disposed often rather than replaced the axles and bearings and all other rotating mechanism in your car frequently. High pressure tires do affect the materials and design dimension of supports and frames of your car.

ICARUS

Any numbers on how much mileage we would get with a higher pressure?

Low rr tires, which incorporate features beyond just higher pressure, typically increase mileage by 1 to 2.5 mpg. The specific figure depends on speed (the higher the speed, the less relative effect of tires because of the overwhelming effect of aerodynamic drag) the weight vs frontal area of the car, etc.

The range in Crr for passenger car tires is .006 to .014... more than a 2:1 difference from best to worst. They are definitely worth using for better mileage (albeit with worse handling, ride, and noise.)

Did you notice that the car reviewers always mention the noise in the cab? It's higher with hard tires. Soft tires really do absorb high frequency road noise. The suspension does the low frequency, because the entire tire, wheel rim, axle, bearings, lower shock, steering arm, etc are unsprung weight, which the suspension and damping have to handle without throwing the car around. Citroen sedans, with their inboard brakes on the front, are very quiet even with overpressured steel belted radials, because they have very low unsprung weight, with their tapered double leading link suspension, even with the outboard universals. They're getting there. My Echo is both noisy and 40mpg economical, due to having little absorbent material to lug around at 2100# and small tires. Worth the noise. A lightweight motorcycle can easily do 100mpg at 50mph for the same reasons.

one thing not mentioned is the feel in cornering, break away of a high press tire is close with no feel just prior to, if you have reflexes like a race car driver you may be okay, at my age I don't drive as hard because my reflexes are slower and would probably see me slipping of the road if I tried to drive like I did at 25, a certain feel for the road just prior to skidding is comfortable and predictable, low profile tires are subject to rock and curb pinch out flats so I like min 15" 205's for the type of driving I do, just overinflated from 28 to 32lbs hot, little harsher ride but better tread wear and rolling resistance, also the tire runs a little cooler, have seen posts where the writer recomends nitrogen filling but I ain't that picky.

Sinc
Mitch retired peugeot mech

Check out the problems that the B58 Hustler had with high pressure tires.