Tire Pressure does make a difference!

[F8L]

I noticed the same thing. With my aftermarket tires they were set up at 38psi and I seemed to have taken a hit over stock rims/tires. By airing them up to 46/44 (tire is max of 50) I have recovered the mpg loss. Next time I'll buy lighter tires and maybe even get better than stock. Maybe lol

[molgrips]

Are the people running 44/42 the same ones that are complaining about the handling and ride of the stock tyres?

My car on my local roads is awful at those pressures. Noisier, harsh, rattley and skittish over bumps. Doesn't feel remotely safe to me when the car wanders going round slow bumpy corners in the dry!

[DougSlug]

There are other variables that will affect your mileage from one tank to the next besides tire pressure. In other words, data on just one tank after changing the pressure may not be conclusive. I have kept my tire pressure constant since I got the car in March (weekly checks or better), and my MPG varies from tank to tank--sometimes to a surprising degree. Temperature, average speed and terrain seem to be the biggest factors...temperature also affects the gas tank bladder volume, which can have an effect on calculated MPG by changing the fill volume slightly from one fill-up to the next, and it determines how heavily A/C is used.

Although tire pressure is known to affect MPG, I am skeptical that it has that great an effect. The problem is that any data used to prove or disprove the hypothesis must also include all the other factors in order to single out the effect of tire pressure. I'd love to see that data, but life's too short.

- Doug

[eak354]

it's long since been established in this forum, and i've been lurking here since way back in '03, that 42/40 is the most common and best tire pressure for improving mpg. (if you don't mind a little bumpy ride) then again, of course terrain, trip duration, driving style, temperature also affect mpg....

[galaxee]

tire breakin also makes a difference

[Etel Rose]

Sorry - what does the dual number mean (e.g. 40/38)?

[mcbrunnhilde]

<div class='quotetop'>QUOTE(Etel Rose @ Sep 4 2006, 06:40 PM) [snapback]314279[/snapback]</div>

Sorry - what does the dual number mean (e.g. 40/38)?
[/b]

The front tires should have 2 psi more than the rear tires--the figures are expressed as front/rear pressures.

[hobbit]

Toyota's "recommended" pressure causes this:

along with low MPG...
.
_H*

[hdrygas]

<div class='quotetop'>QUOTE(hobbit @ Sep 4 2006, 06:47 PM) [snapback]314288[/snapback]</div>

Toyota's "recommended" pressure causes this:

along with low MPG...
.
_H*
[/b]

So Hobbit you must explain to the uniniated what that means? I get it, but I would guess that not everone sees a thousand words.

[Tempus]

<div class='quotetop'>QUOTE(hdrygas @ Sep 4 2006, 09:59 PM) [snapback]314293[/snapback]</div>

So Hobbit you must explain to the uniniated what that means? I get it, but I would guess that not everone sees a thousand words.
[/b]

It means that under-inflated tires wear on the outer edges.

Over-inflated tires wear on the Center.

At Toyota's door-panel Tire Pressures (35 Front, 33 Rear), the OEM tires are decidedly under-inflated by this measure. I can see it every day in parking lots.

I've run mine between 40 and 44 in the front depending on mood (and of course 2lb less in the rear), and I got remarkably even wear. I just replaced the OEMs at 40K miles with 2-3mm left before the wear bars, so I could have technically gotten the expected 50K out of them, but I know that tire performance drops off siginificantly before they reach the 'absolutely must replace' point which is what the wear bars really are.