The science/physics/math/safety behind overinflated tires...

[madler]

<div class='quotetop'>QUOTE(frankk67 @ Aug 28 2007, 07:20 PM) [snapback]503557[/snapback]</div>

can anyone tell me if pirelli p3000 tires would help in mpg?[/b]

I have them on my Prius. They lowered the mileage by about 1-2 mpg. I think closer to 1. I have some uncertainty on that, since there was also a mileage drop at the same time due to hotter weather and use of the air conditioner, and possibly a very small apparent (faux) mileage decrease due to slightly larger tires! But I think I have apportioned the deltas about right.

On the other hand the Pirellis feel so much better -- much more sure-footed. I was happy the pay the mileage penalty. (The before and after tires were both kept at 42/40.)

[madler]

<div class='quotetop'>QUOTE(frankk67 @ Aug 28 2007, 07:20 PM) [snapback]503557[/snapback]</div>

can anyone tell me if pirelli p3000 tires would help in mpg?[/b]

I have them on my Prius. They lowered the mileage by about 1-2 mpg. I think closer to 1. I have some uncertainty on that, since there was also a mileage drop at the same time due to hotter weather and use of the air conditioner, and possibly a very small apparent (faux) mileage decrease due to slightly larger tires! But I think I have apportioned the deltas about right.

On the other hand the Pirellis feel so much better -- much more sure-footed. I was happy the pay the mileage penalty. (The before and after tires were both kept at 42/40.)

[bredekamp]

I always run the tire pressures as stated in the manual. I've done this with all the cars I've owned. Some engineer decided that is the optimal pressure for safety, tire wear, comfort and economy. I didn't design the car and neither did I design the tires. I'll rather trust the engineer who did design them.To think I know better is just stupid...

I'm worried that we're all sacrificing the safety of our families and the lifespan of our tires to save a few bucks at the pump. How 'bout an overzealous insurance company who refuses or reduces an accident payout 'cause they say your tires were not inflated according to manufacturer specs....Huh? Ever thought of that?

Time for TWEELS!! They'll make this whole argument moot.

[brick]

<div class='quotetop'>QUOTE(Albertus @ Sep 14 2007, 05:32 PM) [snapback]512716[/snapback]</div>

I'm worried that we're all sacrificing the safety of our families and the lifespan of our tires to save a few bucks at the pump. How 'bout an overzealous insurance company who refuses or reduces an accident payout 'cause they say your tires were not inflated according to manufacturer specs....Huh? Ever thought of that?
[/b]

This has been covered SO MANY TIMES and even in this thread! "Overinflation" up to the maximum sidewall cold inflation pressure is perfectly safe and for many reasons beneficial. Your family is safe, nobody's insurance company is going to deny an accident payout for having 42psi in the tires. The dramatic BS is getting incredibly old.

[Boo]

Yes. And I don't know if anyone has mentioned this in this thread or other threads, but Volvo and I believe other car manufacturers are in the practice of recommending two levels of pressure -- a lower psi inflation for comfort and a higher psi inflation (but within the tire's maximum psi rating) for fuel economy and wear.

[Allannde]

<div class='quotetop'>QUOTE(Boo @ Sep 14 2007, 05:33 PM) [snapback]512835[/snapback]</div>

Yes. And I don't know if anyone has mentioned this in this thread or other threads, but Volvo and I believe other car manufacturers are in the practice of recommending two levels of pressure -- a lower psi inflation for comfort and a higher psi inflation (but within the tire's maximum psi rating) for fuel economy and wear.
[/b]

You are absolutely correct which points out just why Toyota recommends the lower tire pressure on the Prius.

Anyone who reads this whole thread will get a fine education on the subject. There really isn't much more to say.