New Pirelli Tire Won't Hold Air Pressure?

Discussion in 'SRT Hellcat Wheels and Tires' started by rollieman, Jul 3, 2016.

  1. rollieman

    rollieman Silver Member

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    Just purchased a new set of Pirelli 275/40/20 P-Zero summer tires for the backs along with a new set of factory Mopar Hellcat rims plus new Mopar TPMS sensors 56029400AE.

    Had them installed at a shop with a touchless tire machine which went flawlessly.

    This morning took the Hellcat out to go to a car show and one of the new tires was half flat !!

    I immediately pumped back up to 32 PSI and re-tightened the sensor nut which seemed kind of loose thinking this may be the problem.

    The tire held fine at the show then after I brought it home I noticed it had lost 5 PSI down to 27 PSI cold --- I pumped it up again to 32 then re-tightened the sensor nut again as much as I dare to go and it's lost another 2-3 PSI in about 2 hours.

    Obviously something is wrong but not sure where to start ??

    I do remember the tech telling me that he was unable to use the small washer that came with the TPMS assembly because it didn't allow enough threads to catch the TPMS nut so he left it out ---- could this be the problem???

    Any ideas would be much appreciated!

    Note: I just put my jack under the black jack pad to prevent damage if it continues to loose any additional pressure through the night.
    Thank you !
     
  2. blaze

    blaze ☆★✪ The Watcher ✪★☆ Hellcat Car Club Gold Supporting Member

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    rollieman i see nobody has replied to your thread so i will give it a shot (best guess)
    get a spray bottle and use dawn or something to make some soapy water and spray down the tire and see if you have some soap bubbles coming from any location to try and spot the air leak.
    not sure about your sensor nut missing.. try and keep air in it and head on back to the shop if you cannot figure it out assuming there are no nails or punctures..
     
  3. rollieman

    rollieman Silver Member

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    Thank you Blaze, I'll give that a try today ---- the tire had zero miles on it so shouldn't be a nail. If the leak shows up at the sensor stem I'll get a sensor service kit before I bring it back to the shop (Mopar # 68020719AC). The other new tire is fine as it should be.
    It's frustrating because I didn't skimp on anything; new Mopar Hellcat rims, new correct Mopar sensors and new Pirelli tires and STILL something has failed! :(

    I'll keep you posted.
     
    Last edited: Jul 4, 2016
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  4. rollieman

    rollieman Silver Member

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    Excellent idea with the soap spray because it immediately showed a serious leak at the base of the sensor stem where it butts against the rim.

    So I'll pick up the Mopar service kit for that sensor.

    I'm still puzzled what the purpose of that small washer that came with the sensor kit is for ???

    I agreed with the tech that if you use the washer there was barely one thread showing on the outside of the rim which would not allow the sensor nut to even start, so when we removed the washer then it was fine.
     
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  5. Steppenwolf

    Steppenwolf VIP Hellcat Member

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    Guess I missed this on the first read thru .... I've got P-Zero summers on the stock factory matte black alum wheels on my 2016 Cat.

    So, if I understand correctly, you bought different (Mopar) rims and then had your P-Zeros installed on them? If so, I'd suspect either a nail/screw or a rim leak.
     
  6. rollieman

    rollieman Silver Member

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    Yes I purchased an extra set of factory rims to mount the summer tires for the back only --- the fronts are P-Zero Nero all seasons. When the temps go below 40 degrees I will swap back the AS Nero's. Wound up being a leak at the base of the sensor stem.
    Thank you !
     
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  7. Steppenwolf

    Steppenwolf VIP Hellcat Member

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    Okay, good to hear you got the problem identified. Thanks!
     
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  8. MABBRYFL30

    MABBRYFL30 NYS President Hellcat Car Club Gold Supporting Member

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    Get a soapy solution and soak down the bead, sensor and tire tread to find your leak.
     
  9. MABBRYFL30

    MABBRYFL30 NYS President Hellcat Car Club Gold Supporting Member

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    Good idea down the road or next time at dealer to out nitrogen in the tires.
     
  10. Tire God 2.0

    Tire God 2.0 Senior Hellcat Member

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    The tpms kit that replaces the rubber seal, washer, valve core and cap should be used every time a tire is dismounted for any reason. Just like changing the rubber valve stems every time. The tpms nut has a specified torque that it must be torqued to(usually 40 or 50 in/lbs). Not tight enough and it causes a leak, too tight squishes the rubber seal and causes it to leak. The washer is there to ensure proper torque specs, and so the nut doesn't dig into the valve hole. Just like any other nut/washer combo that exsists. The shop SHOULD have the proper tpms equipment. But you never know.
     
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  11. Steppenwolf

    Steppenwolf VIP Hellcat Member

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    Stupid noob question, but you talking about when the tire is removed from its wheel/rim, correct?
     
  12. Tire God 2.0

    Tire God 2.0 Senior Hellcat Member

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    Yes. Any time we replace a tire or do a flat repair, we rebuild the components of the tpms or replace the rubber valve stem. Just good practice. Mainly because the tire can apply pressure to the sensor when being dismounted, and can cause it to unseal.
     
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  13. Steppenwolf

    Steppenwolf VIP Hellcat Member

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    Okay, thanks. Just looking learn all the tire nuances, but initially I thought you meant the tpms kit was required like when a simple tire rotation is done. Now I understand ...
     
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  14. rollieman

    rollieman Silver Member

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    Apparently the problem wound up being the rubber seal which was included in the TPMS service kit, after it was replaced it was fine.
    Also no codes with the new Mopar TPMS.
    Thank you all for your help !
     
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  15. rollieman

    rollieman Silver Member

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    [QUOTE="Tire God 2.0, post: 426706, The washer is there to ensure proper torque specs, and so the nut doesn't dig into the valve hole. Just like any other nut/washer combo that exists.

    I agree 100%, however, in this application it appears if you use the washer there's barely one thread showing through which won't allow the nut to even start.

    Also when I checked my front factory Hellcat tires & rims I was unable to see any washer used as well?

    As I recall this TPMS (56029400AE) is used in several different Chrysler cars.

    Is it possible that the Hellcat rim is thicker, thus not allowing sufficient space to use the washer???

    Thank you!
     
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