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Discussion Starter #1
Hi all,

I have a question about inflating the tires over the what is stated on the sidewalls.

I have a 2007 Prius. The PSI on the tires is 44. I have read that increasing the PSI in the front tires can increase mileage, however I have not read anything for the PSI on my tires. It seems from what I read that it folks inflate about 2 PSI over what is on the sidewalls in the front. Thus, I recently increased the PSI in the front to 46 and left the back at 44. I worry that maybe I should not increase the PSI over what is stated on the sidewalls. Does anybody know about this???? If so any suggestions on PSI.

Thanks!

daktron
 

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daktron said:
Hi all,

I have a question about inflating the tires over the what is stated on the sidewalls.

I have a 2007 Prius. The PSI on the tires is 44. I have read that increasing the PSI in the front tires can increase mileage, however I have not read anything for the PSI on my tires. It seems from what I read that it folks inflate about 2 PSI over what is on the sidewalls in the front. Thus, I recently increased the PSI in the front to 46 and left the back at 44. I worry that maybe I should not increase the PSI over what is stated on the sidewalls. Does anybody know about this???? If so any suggestions on PSI.

Thanks!

daktron
Daktron,

NEVER inflate your tires above the sidewall MAX cold air pressure as that is not safe. The usual advice here is that the front tires should be 2 psi higher than the rear in a Prius. It is true that the manufacturers tend to suggest a lower air pressure than what most of us feel is best for MPG, handling and tread wear. I run my tires at 42/40 as I have all three brand/models that I have used (Goodyear Integrity, Michelin MXV4+ and now Nokian WR). The first two had a sidewall rating of 44 psi. The Nokians are rated at 51 psi, but I still run them at 42/40 so MPG comparisons will be legitimate.

JeffD
 

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Discussion Starter #3
Jist to confirm. Should I inflate the front 44 and the back to 42? Thanks for the quick response!
 

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daktron said:
Jist to confirm. Should I inflate the front 44 and the back to 42? Thanks for the quick response!
Keep a 2 psi differential between the front and back. The front should always be 2 pounds higher than the back.
 

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Discussion Starter #6
got it. its ok to under inlflate but not over inflate. 44 PSI in front and 42 PSI in the back!
 

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got it. its ok to under inlflate but not over inflate. 44 PSI in front and 42 PSI in the back!

Not you have it backwards, It is OK to overinflate but not OK to Underinflate!
 

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Rickey, it is NOT ok to over-inflate. You should not exceed the max pressure listed on the sidewall of the tire.
 

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firepa63 said:
Rickey, it is NOT ok to over-inflate. You should not exceed the max pressure listed on the sidewall of the tire.
I meant, overinflate from Toyotas service across the nation recommendation of 35 psi all around to up to 45 psi in the regular Prius with the Good Years and up to 50 psi on the Touring with Bridgestone tyres. NOT to over inflate from tyre manufacturers spec.
 

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hyperion said:
That's right and Toyota engineers for overall handling, traction and safety suggest on your door sticker to inflate 35 frt/33rear.
This 44/42 figure comes for an extra MPG and riding on rails handling. (you could develop "rattles" in the dash board at the higher pressures)

Heck, if I wanted a mushy ride and crappy mileage, I would have bought a Lincoln. Pump it up and save a soldier or two.
 

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You really "got to be kidding." There is absolutely nothing you can do to get a "soft" ride" in the prius.
I have heard of no other car out there that stipulates more than 30 psi in the tires. The fronts in my Highlander stipulate 28,, as do the fronts in my Cadillac. Both, front wheel drive.
For "maximun" loads in my old pickup, the manual states to pump up the tires to 30 front and 28 rear and thats RWD. (Otherwise for handling purposes, the door sticker stipulate 26/24.
The factory figures for the Prius are way above standard to begin with. Individual owners have opted for the much higher pressures and If I lived in an Area like Arizona, Texas ect; where high summer temperatures are the norm I'de be darn carefull what I put in my tires.
 

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When did they change the Highlander to a front wheel drive vehicle?

(Oops) Just realized that I was thinking of the 4Runner. Sorry.
 

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The higher pressures are actually safer during hot summer weather, as there is less sidewall flex and generated (internal) heat. Lower pressures (in the mid-20 psi range) actually contribute to belt slippage, tread separation and blowouts. Next time you drive through the desert areas, just look at all of the dead "(alli)gators" on the our highways.

After the Firestone problem, ADOT (Arizona Dept of Transportation; a.k.a, highway patrol) put out a statement that the most common cause of tire failure in Arizona was underinflation, and told everyone to pump up their tires.

I run 46/44 in my HydroEdges on my 2002 Prius, and the 1978 Chevy pickup (that has load range E tires rated at 80 psi) have 55/50 in them. Even the pickup gets better mileage and more even tirewear at the higher pressures (if you can call 8 mpg versus 7 mpg an improvement, though that's around 14%). I even run 65 psi (the max) in the tires on our Airstream.
 
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