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Uneven tires

Discussion in 'Gen 3 Prius Fuel Economy' started by nooaah, Mar 25, 2010.

  1. nooaah

    nooaah New Member

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    Let's say someone's left front tire is 43psi and the right front is 42psi--that someone being me. Safety concerns aside, what sort of effect could this potentially have on your mileage?

    I found my tires to be off by 1-2PSI on each side recently. Obviously I evened them out immediately, but it made me wonder if I could've lost a significant percentage of potential efficiency. Thoughts?
     
  2. mad-dog-one

    mad-dog-one Prius Enthusiast

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    I think there is 1 to 2 pounds of random error in most tire pressure gauges, so you shouldn't expect to get an exact measure that is more precise. Furthermore, your tires will differ by a couple pounds of air pressure if some are in the sunlight and others in the shade. I wouldn't worry about 1 pound difference in tire air pressure.
     
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  3. tumbleweed

    tumbleweed Senior Member

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    Not a problem, as mentioned above they change more than that if the sun shines on one side for a while. Radial ply tires don't grow in circumference the way bias ply tires did with increased pressure. Just set them to within a pound of each other in the morning when they are cool and you should be OK. A lot of people are probably driving around with tires that are not within 10 or 15 lbs of each other and don't even know it. :eek:
     
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  4. jdcollins5

    jdcollins5 Senior Member

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    Tumbleweed,

    The issue with the sun shining on one side for a while is something that I just recently discovered. Since I have purchased a 0-60 psi tire gauge where you can really see the difference in 1 psi I have noticed that the tires on one side read 1-2 psi higher than the other in my driveway. That is when I noticed that the sun hits only one side of the car in the morning. Turned the car around and an hour later the other side read 1-2 psi high. Amazing discovery !!

    Sorry nooaah, didn't mean to steal your thread !!

    Dwight
     
  5. nooaah

    nooaah New Member

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    Haha go for it. This site is all about learning everything possible about our cars. :)
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    1-2 PSI shouldn't be an issue. The fronts should be 2 PSI higher than the rears anyway.
     
  7. nooaah

    nooaah New Member

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    Yeah, I just meant a slight variation from one side to the other. I run my Gen3 at 44/42.
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    wow... I run mine 40/38 (38/36 on the Gen 2's WRs)
     
  9. jdk2

    jdk2 Active Member

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    Same here. 44/42 must be like riding on concrete tires :p
     
  10. nooaah

    nooaah New Member

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    Haha, I honestly haven't noticed much of a difference.
     
  11. jdcollins5

    jdcollins5 Senior Member

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    I thought the same thing when I first got the Prius. I took the pressure to 40/38 and thought that was about as hard as I wanted it. Now that the temperature has risen substantially my tire pressure has slowly increased to over 42/40. When I checked it last weekend, I decided to leave it at 42/40 since I had gotten used to it. It is surprising to me how quickly I have gotten used to the higher pressure. I have even raised the pressures in my wife's 2007 Honda Accord to get more wear in the middle of the tire.
     
  12. mmichaell

    mmichaell Member

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    I could be wrong, but last week when temps rose from 30s to 60s it felt as if the tires were more comfortable (I always keep them at 39/35 cold presssure). So maybe heat has something to do with the comfort as well - more pliable tires maybe?
     
  13. jdcollins5

    jdcollins5 Senior Member

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    You are correct about temperature having an affect on the comfort, especially the first few miles. A cold tire feels a whole lot harder than a hot tire. When I first drive off in the morning, and even in the afternoon, the tires feel really hard. Once the tire gets up to temperature, it feels much better.