Okay, I've had my Prius over a month now and I checked my tired pressure yesterday. The first thing I noticed was how low the factory default tire pressure must be. My front Tires read 36 and 35 and the two back tires read 32 and 34. Judging by this, I am guessing the factory default is 36/34, or thereabouts.

Does anyone know what the factory defaults are?

Knowing that I have been getting around 60mpg the last two weeks or so, I am going to raise my tire pressure to 40/38 to see how my mileage may change to do some testing myself.

I am wondering if any detailed analysis has been done comparing the relation of MPG and tire pressure. I know that many have said their higher tire pressure has resulted in higher FE, but I have not seen any graphs or reports on this topic in detail.

Assuming that you have the standard Prius (not the Turing) and you have the stock Goodyear Integrity tires, the default PSI is 35/33 as shown on the driver's door jam. I ran mine at 42/40 which is still below the MAX rating as shown on the tire sidewall. They were worn out at 44,500 miles and my present tires (Michelin MXV4+) are at the same PSI and now have 49,000 on these great tires, but will probably have to replace them this fall.

JeffD

Thanks for the details.

The sidewall indicates 44 max PSI in the tires I have. I believe they are Goodyear, but I forgot to check while my brain sidetracked

The factory recommended are found inside the door jam, but its fairly safe to go up the max sidewall pressure on the tires, this is safer and more efficient, but the ride is not as smooth, if you want to play it very safe go somewhere in between these two numbers, but unless you find the ride to become annoying, a higher pressure than the recommended is fine.

Many people say that you can exceed the max sidewall, but i just dont think that it is a good idea, its up to you though!

4/27/08 612.1 miles @ 62.1 MPG with 110,000 miles on the Civic

Yeah, I definitely feel better staying below the max

The car is significantly more sensitive to crosswinds when you jack the tire pressure up so I reluctantly dropped mine back to 38/36, from 42/40. Made a noticeable difference and improved the ride as well. Cost me 2 mpg overall - I can live with it.

Hi Battery Buddies - I noticed all you'all are showing a differential with the front higher. I am running the other way on my Touring - 44 front 46 rear to cut down on the wind sensitivity. I'm wondering what I'll do for snow tires - I go to work every day, and we do ocassionally get snow and ice. The traction control works more often that I would have guessed, even on dirt, and wet stripes. The bottom drops out until the spinning stops - so, I am learning not to jump out in front of on-coming traffic if it's wet out. One thing I've always had on front wheel drive cars before - a hand brake! Makes it MUCH easier to maneuver. Probably wouldn't work with traction control, though. Foot brakes suck! Anyway, can't wait for winter.

BeechSportBill
2007 Prius Touring Package 6

I don't think anyone has done a study to find out what works best. For me, it is a questions of weight distribution. A tire with higher pressure can handle a heavier load and the front wheels carry more weight.

What I'd like to suggest is to get a fast sensitive temperature gauge, you could study the temperature distribution of the front and rear tires. The goal is to get equal temperatures across all treads and equal temperatures front and back. For example, an infrared temperature probe works great.

Bob Wilson

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You can safely put 50psi in the tires. The burst rating is much higher. The factory uses a compromise between comfort, road handling, tire wear and mpg. I bought a Prius for gas mileage, so the higher psi is what I use.

I agree Resist. I run my 51 PSI max Falkens at 55/53 PSI.
I am still breaking them in and expect mileage to edge
back up in about 4000 more miles

My previous set were GY Intergitys (44 max PSI) and I
ran them at 50/48 PSI and got 55,000+ miles out of them.

Alden Bowles
2005 Toyota Prius II HSD