An Article on Over Inflating Your Tires

[Don]

Found this online today under "Ten Things You Should Never Do To Your Car"

Never Overfill the Tires to 'Get Better Gas Mileage'

The Internet is brimming with testimonials from people who claim they upped their mileage simply by inflating their tires to the maximum pressure listed on the sidewall. What they don't tell you about is the rougher ride, premature tire wear, longer stopping distances and increased repair costs due to worn-out suspension components. The recommended tire pressure for your car is listed on a placard inside the driver's door frame and it's based on vehicle weight along with the best possible handling. Inflating your tires to the maximum pressure listed on the tire is okay if you're hauling a very heavy load. But you must reduce the tire pressure to the recommended pressure once you remove the load. Driving a normal load on over-inflated tires reduces rolling resistance and that can increase your mileage slightly. That means you have less rubber in contact with the road, which reduces traction.
Over-inflation increases stopping distances, causes the tires to slip and hydroplane on wet roads and reduces the life of the tire. The much harder tires also absorb less impact vibration so they transmit more road shock to your entire suspension system, causing a rougher ride. Worse yet, the additional tire bounce wears out your car's struts, strut mounts, shocks, springs, ball joints and control arms much faster. Any mileage gains you get from decreased rolling resistance are more than offset by decreased safety factors and increased suspension repair costs.

Don

 

[joev]

Excellent find Don.
Just replaced the stock tires with the Yokohama Avid Envigor and yes there is about a 10% REDUCTION in range. Tried different tire pressures but no significant difference.
Thanks again for all you do to keep us informed and in line.
Joe

 

[kiev]

The internet is brimming with folks typing themselves smart...

Don't know who wrote that article but i doubt he has any data to prove that over-inflated tires will increase suspension repair costs--but it sounded good when he wrote it.

i'm just a redneck with a library card--and from a math and physics point of view (spring-mass-damper 2nd order linear differential equations), tires are modelled as springs and increasing the air pressure causes an increase in the stiffness coefficient, K. But the force transmitted across the spring (tire) doesn't change, only the spring travel (compression) distance changes, X = -F/K. Increase K decreases X, but the Force is the same no matter what the tire pressure. Shock absorbers provide the damping, not the tires. Excess potholes and curbs increase suspension repair costs.

@Joe, i put Yokohamas on too, and run the pressure at the max, and drive 40 to 60 miles every day--i'm getting RR in the high 70's and low 80's every morning, while running the AC and driving fast on the interstate too. Check your wheel alignment?

 

[JoeS]

Hi Don, I might add that it's good form to also provide a link to the source article, in addition to quoting from it.

I've gone back to my unruly ways and have increased the pressure on my inexpensive front Blizzaks to their maximum 44psi sidewall pressure (still a compromise for me) with the beneficial result that my unnecessary ASC has stopped kicking in (due to the tire mismatch).

 

[Don]

Here's the source of the article

https://www.msn.com/en-us/autos/ownership/10-things-you-should-never-do-to-your-car/ss-BBLG50T?li=BBnb7Kz

Much of what is there is true - Over inflated tires have a smaller contact patch (which is responsible for the slight improvement in range) and that also means less traction and poorer handling. The tires, their pressure, the suspension geometry, the shock valving, the weight of the vehicle are all part of the engineered values that make for a good or a poor handling car. To jump in the middle of the 'soup' that the engineers designed and make a major change to one or more of the parameters probably has consequences - If you think not, it's your car and you should do what you feel is best

Don

 

[ed5000]

Excellent find Don.
Just replaced the stock tires with the Yokohama Avid Envigor and yes there is about a 10% REDUCTION in range. Tried different tire pressures but no significant difference.
Thanks again for all you do to keep us informed and in line.
Joe

Did you take into consideration tire diameters between old tires and new? I replaced all four tires last September with same tires, Yokohama Avid Envigors, and took a mileage hit but I believe the old tires were over-reporting miles a little.

Now after a year on my Yokos I get into the low 70's on the range remaining gauge after a full charge which is about what my original Dunlops reported.

 

[Don]

Did you take into consideration tire diameters between old tires and new? I replaced all four tires last September with same tires, Yokohama Avid Envigors, and took a mileage hit but I believe the old tires were over-reporting miles a little.

That's certainly part of it - Old, worn, nearly bald tires do make the computer think the car is going farther than it actually is . . . . and then when you replace them with full tread depth tires, the difference in how far you actually are going is pretty dramatic . . . . but I don't think it accounts for all of the loss

Don