Max Sidewall Pressure...

They are two names for the same thing. It has been covered in many threads. You will be able to find them with the search feature.

 

Yes, the Maximum pressure listed on the tire itself is commonly used as a guide to inflate Prius tires. Toyota's reccomendation on the driver's door jam, yeilds a smoother ride, but less tire life and lower mileage. It is common to inflate the rears two pounds less than the fronts. (I use 2 pounds less than the max in front and 4 pounds less than the max in back)

 

If your roads suck, max sidewall pressure will let you "feel" more of the bumps (all of em).

 

"Max. sidewall pressure" will also decrease traction and increase stopping distance, tradeoffs which IMHO are not worth the fractional increase in MPG.

 

You ran tests on a Prius? Can we see them?

 

My 2006 had better traction on wet pavement at max sidewall pressure. I never measured stopping distance.

The only time my 2010 was intentionally below max sidewall was on the first trip home from the dealer.

The attached file is a professional's point of view.

 

Several NASA and aviation sources, as pointed to in earlier posting on this subject, show that higher pressures improve hydroplaning resistance. In my climate, this is important.

 

Yes, but only with regard to underinflated, not properly inflated, tires. Also, isn't difficult to fly and hydroplane at the same time?

 

Good article from the police perspective, but he is speaking of a tactically loaded police package Crown Vic. Having owned two Crown Vics with performance and handling packages, I can tell you that the Prius is NO Crown Vic.

 

Aircraft have devices called brakes at the wheels. They aren't effective when hydroplaning. They are important enough that ABS was used on aircraft before cars. When no longer flying, aircraft are also steered by the wheels and depend on the wheels for directional stability.

 

Do you have any "studied evidence" that you can reference or share?

There is another thread, MPG difference between recommended and max tire pressures?, that is asking for data on mpg differences.

http://priuschat.com/forums/gen-iii...e-between-recommended-max-tire-pressures.html

 

What "articles and physics" are you refering to? I would be happy to be educated and converted to your opinion if you can reference or post authoritative and convincing documentation. BTW I am very familiar with the NASA folks, having been at Goddard on a number of occassions and knowing people who do good work there.

 

If that is true, then the door placard psi recommendation on my old Honda (before the Explorer rollover problem surfaced) was simply wrong. Hydroplaning in that car is what lead me to this issue.

The hydroplaning resistance formula in the mentioned articles has no cap at any 'properly inflated' pressure.

Use the PriusChat 'Search' function. This issue repeats several times per year.

 

Its not clear to me what you are trying to say in your first statement, but I happened to receive this newsletter Best Tires for Bad Weather - December 2010 - Eriesense.com from Erie Insurance today which says:

"Find the tire pressure number for your vehicle on the driver’s side door or in the glove compartment. It’s not the number on the tire sidewall. That’s the “maximum permissible” for that tire. The vehicle manufacturer determines the correct tire pressure for your vehicle. Why? Because proper pressure is based on vehicle design load and tire size."
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Also, what "mentioned articles"? You want me to search to make your point? Please!!!

Everything I read and hear from reputable and authoritative sources says to follow and use the auto manufacturer's recommended tire pressures, not the maximum pressure on the tire sidewall, as confirmed again in the above Erie Insurance article. I need something more definitive and authoritative to the contrary before I can change my opinion on this one.