1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Delivered Tire pressure - way too high?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by rflagg, Mar 25, 2004.

  1. rflagg

    rflagg Member

    Joined:
    Jan 5, 2004
    947
    9
    0
    Location:
    Springfield, VA
    So, I finally found a gas station yesterday that doesn't charge you for using their air to fill the tires. So, I stopped there on my way home from work (mind you, the car had been running for 35+ minutes).

    Checked the pressure on the driver left front tire - came out as around 45psi! So, I lowered it to 41psi. Same case for the driver side rear tire, measured at 45, lowered to 41 (later lowered at home when the car was cool to 39). The passenger side tires both came in around 50psi! Could this have possibly been so high because of the car being 'hot', and the fact that there was no passengers in my drive and a box of approx 40 lbs on my side in the back as well?

    Regardless, I lowered all 'hot' tire pressures to 41, then lowered the rear two tires to 39 once the car had cooled at home. Has anyone else come across extreme tire pressures, or anything that could explain this? Thanks!

    -m.
     
    #1 rflagg, Mar 25, 2004
  2. jasond

    jasond New Member

    Joined:
    Mar 5, 2004
    165
    0
    0
    Location:
    Boston
    What did you use to measure the pressure? The built-in pressure gauge at the gas station air pump? Are you sure it's accurate?

    (If you were using your own gauge, I assume you just would've checked the pressure at home before it got to that point?)

    Check all the tires again cold to make sure they're where you want them to be. Mine are and have been 35/33, but I'm raising that to 40/38 as soon as I have a few free minutes...
     
    #2 jasond, Mar 25, 2004
  3. rflagg

    rflagg Member

    Joined:
    Jan 5, 2004
    947
    9
    0
    Location:
    Springfield, VA
    I used a simple store-bought pen style tire gauge that I picked up a few days ago.

    -m.
     
    #3 rflagg, Mar 25, 2004
  4. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    -m
    It's tough to know, it does seem odd that passenger vs driver side pressures were so disparate. You REALLY should have checked that on your own soon after you got the car home. BTW, have you checked the oil level yet? Mine was delivered at about 1cm over max. full--I took it in to have it drained down to just below full.

    Remember, check tires cold, and oil warm. Consider buying one of the nice portable air compressor/jumper battery/safety light combo units (I got a nice one at Sam's for <$50) so you can check tire pressures cold, at home, and air them properly. As the tempertures warm then cool this is something you should be doing on a monthly basis at least and more often if there's a significant change in the average daily temperture.

    Also, be sure you maintain the pressure differential--front with 2psi more than rear. I stick with 42f/40r so I have a margine of safety if the tempertures go up and stilll have them high enough when the temps go down. 40/38 is a reasonable and conservative starting point as well.
     
    #4 efusco, Mar 25, 2004
  5. rflagg

    rflagg Member

    Joined:
    Jan 5, 2004
    947
    9
    0
    Location:
    Springfield, VA
    Evan,

    Yes, I was expecting to have the standard 35/33 that seems to come 'off the boat'. I have checked the oil level, which seems fine (right around max fill line), but now I'm definately going to invest in a small portable air compressor to be able to fill/check at my leisure. It did seem odd to me to have such a differential from one side to the other - again, my only thought that it could be the weight on the left side of the car (I only weigh about 160lbs, and the box in the back is around 40lbs, so you'd think it wouldn't make that much difference?) - hence why I asked. Needless to say, I certainly noticed a more smooth ride this morning. (Oddly enough, close to the same mileage, but it is warmer outside too)

    -m.
     
    #5 rflagg, Mar 25, 2004
  6. jasond

    jasond New Member

    Joined:
    Mar 5, 2004
    165
    0
    0
    Location:
    Boston
    Fyi, I just picked up a DC-powered compressor on sale at Radio Shack for $20. I think the regular price was $40.
     
    #6 jasond, Mar 25, 2004
  7. efusco

    efusco Moderator Emeritus
    Staff Member

    Joined:
    Nov 26, 2003
    19,891
    1,193
    9
    Location:
    Nixa, MO
    Vehicle:
    2004 Prius
    Model:
    N/A
    Yea, the compressor alone versions can be had in the $20 range. I really wanted the one with the built in jumper battery and cables though since the 12v battery on the Prius has been known to die if the car is left with the SS/E left on for extended periods of time...I wanted to be able to jump it myself at home quickly. Also, the jumper has already come in handy once for my wife to use on her minivan and avoided a major problem...she knows nothing about cars and yet was able to manage that.
     
    #7 efusco, Mar 25, 2004
  8. SpartanPrius

    SpartanPrius New Member

    Joined:
    Dec 31, 2003
    107
    0
    0
    Often, the difference from side to side could be related to the amount of sun exposure a car receives while parked. A 5 lb differential would be at the upper end of this influence. And, the fact you had already driven "35+ minutes" would rule this out. Still, be aware of this potential influence whenever you do a cold tire check.

    Dealerships and any other tire related mechanics are often negligent when it comes to tire pressure. Frequently, they won't even check, or they'll simply fill to the maximum cold pressure value stated on the tire sidewall. What can aggravate this situation further are the ones who do this while the car is still off the ground. Also, keep in mind that a car "fresh off the boat" would have been pre-filled in Japan for transport only. It's up to the dealer to deliver a properly prepped car.

    And for those who choose to elevate their cold pressure towards the maximum cold pressure value. You should consider that a 2 pound front to rear differential proportionally becomes a 3 pound differential at that level.
     
    #8 SpartanPrius, Mar 25, 2004
  9. RobertO

    RobertO New Member

    Joined:
    Nov 26, 2003
    215
    1
    0
    Location:
    Renton, WA
    This month Sears has had a remarkably accurate and easy to use digital Pressure Gauge on sale for around $ 8.00. I think they usually retail there and elsewhere for $ 10 - $12.00.

    It's rather slender, so lays down in the top glove compartment necely with room to spare.

    I'm running the 42/40 Front/Rear settings. Seems just right.

    Next step will be installing a Futomo Oil Drain Valve and Mobil 1.

    Little steps towards automotive Ninvana....


    Bob
     
    #9 RobertO, Mar 25, 2004
  10. rflagg

    rflagg Member

    Joined:
    Jan 5, 2004
    947
    9
    0
    Location:
    Springfield, VA
    Radio Shack is running their Coleman 5-in-1 250psi air compressor/emergency light/etc for $20 bucks this week, down from $41, in case anyone else needs to pick one up.

    -m.
     
    #10 rflagg, Mar 26, 2004
  11. jasond

    jasond New Member

    Joined:
    Mar 5, 2004
    165
    0
    0
    Location:
    Boston
    Yeah, that's the one :)
     
    #11 jasond, Mar 26, 2004
  12. daniel

    daniel Cat Lovers Against the Bomb

    Joined:
    Feb 25, 2004
    14,487
    1,518
    0
    Location:
    Spokane, WA
    Vehicle:
    2004 Prius
    I got a cheap 12-v compressor from Sears, I think it was around $20. Went home and decided to bump up my tires to 42/40. It took forever to get from 35/33 to 42/40. That thing was SLOW!!!

    I returned it and got a more expensive 110 v compressor instead. I have not tried it yet.
     
    #12 daniel, Mar 26, 2004
  13. N9IWP

    N9IWP New Member

    Joined:
    Jan 20, 2004
    148
    1
    0
    Location:
    Southeast MN
    #13 N9IWP, Mar 26, 2004
  14. Ken Cooper

    Ken Cooper New Member

    Joined:
    Mar 4, 2004
    339
    5
    0
    #14 Ken Cooper, Mar 26, 2004
  15. RobertO

    RobertO New Member

    Joined:
    Nov 26, 2003
    215
    1
    0
    Location:
    Renton, WA
    I check the URL in your post. Yep, that's the one from Sears.

    Very easy to use. Slips into the upper glove box no problem.

    I've seen it elsewhere for $ 10 to $ 12 bucks.

    I like it. Got me flat on the money at 42/40 front/back.

    By the way; I'm using a larger compresser, a Porter-Cable, capable of 120 psi. good all-around rig for blowing off your bench (wear you glasses or goggles), cleaning out tractors and lawn mower decks. Will drive smaller nair and brad guns nicely.

    It's very cool.

    It's red.


    Bob
     
    #15 RobertO, Apr 3, 2004
(You must log in or sign up to post here.)