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Why 65psi max for dually rims?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Cubey, Aug 9, 2019.

  1. chillman88

    chillman88 Supporting Member Supporting Member

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    The 4x4 dually trucks came with 235s so if you can find a factory cab and chassis 4x4 dually you "should" find the wheels with the higher offset. Keep in mind that a lot can change over 20-30 years though so make sure you measure to verify.
     
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  2. Cubey

    Cubey Full Access Member

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    Usually junk yards immediately pull the tires/wheels off, especially if the tires are worth selling. Even when they don't, they have the truck raised with the lug nuts still tight so you can't get the lug nuts off. I'd need 7 of them too, 6+spare. Too much extra cost, about $200 with tax for used wheels.

    I'm not worried about 215s not being able to carry the proper load per say. They are what's called for by El Dorado when they did the RV build, so it should be fine. I did want 80psi for stiffer sidewalls etc but since the wheels spec 65 max, I'll run the tires at that. 65 should still be fine. I'm just running Load Es at 65psi instead of load Ds at 65psi.
     
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  3. raydav

    raydav Full Access Member

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  4. Cubey

    Cubey Full Access Member

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    There is sign on one side of the inner tire blowing out, the not very strong under skin metal and rigid foam inside has a damage spot like a piece of tire hit it. It could be a big rock or other road debris did though, considering how small the area is.

    TMPS lets you see the pressure while driving down the road, so you can potentially help prevent total tire failure before it happens, if it's just a nail.

    I've never had a blow out, but I had a TON of flats from screws being dropped in the road around where I lived. I had 4 flats on one car and 1 flat on a van. I know no one was screwing them in by hand, because the van's tire screw was on the bottom against the ground where I had parked overnight when I had road side come change it for me. The day before it was fine.

    I was a passenger in a friend's Taurus when it had a front right blow out at around 70mph. His natural reaction was to hit the brakes and I was like "no! stay off the brakes! let it coast to slow down". Thankfully we were only 1/2 mile or less from an exit so he limped it along to a gas station off the exit. That was preferable to changing the tire on the side of a 75mph interstate where the usual shitty people were doing 80 or more.
     
  5. raydav

    raydav Full Access Member

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    I have had several tires that looked like this by the time I got the vehicle stopped.
     
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  6. Cubey

    Cubey Full Access Member

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    All my flats were found when it was parked after sitting overnight. Never had a flat while driving. Lucky lucky I guess. I do try to remember to watch my tires though. I don't was much as I should though.
     
  7. typ4

    typ4 Supporting Member Supporting Member

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    I didn't read through all of this but for what it's worth I put 235 all the way around on the dually it's an 88 Calvin got me some commercial grade front tires like he ran on his tow trucks cuz we had a separation and he told me to run out what I had on the rear and then make damn sure and get a commercial grade Tire in thata 235,w the casing is stiffer that keeps it from poochin. they wouldn't Pooch with the camper on and he said running 80 psi in the wheels is not an issue he did it for years.
     
  8. PROFG

    PROFG Registered User

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    Side note from more than 6 freeway blowouts showing wheel strength (not dually or Ford but I think appropriate). Half ton '59 Chevy Apache 3200, stock wheels, 125psi, 1/2" rear axle travel till OL coil bound, freeway speeds, and 9400# on scales. Ran from Oregon with no problems until Indiana / Ohio concrete slab raised edge bumps. After going "off road" at speed first time learned feel of impending blow out (wishy washy feel to rear). Blew out/ruined 6 or 7 wheels by Pennsylvania. Wheels would "spread apart" between beads and pinch tube. At lower pressure tires would overheat. Weight on rear about 70% of 9400 so 3290 on Wards 4ply / 6pr Light truck tires. They held up thru it all. With 2 more wheels could have reached CT. Kept last wheel as memento and lesson learned.
     
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  9. Cubey

    Cubey Full Access Member

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    Eesh. It seems as though dropping the rears to 65 has lost me 1-1.5mpg hwy. That's a huge loss! I'm getting about 8mpg now. I was getting about 9-9.5 at 80psi. Looking back at fuelly, I was getting worse mpg back before I put it up to 80 too.

    I think I will put them back to 80 despite the 65 rim and just cross my fingers. It seemed fine for the 500 miles i had it at 80.

    1-1.5mpg is a big deal when we are taking single digit mpg. 1mpg improvement 8.2 vs 9.2) per 1000 miles is about 14 gallons in fuel savings, $40 give or take.
     
  10. Cubey

    Cubey Full Access Member

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    I was a half mile from a free air hose so I went to it earlier. The rears were showing 70 after the half mile drive, when they should be at 65. So accounting for that, i filled them to show 80, meaning they should be roughly 75 cold.

    I almost left without checking the fronts. Glad I didn't, both were showing about 54!! Factoring in the short drive, they were probably about 15psi low! I filled them to show 70, so they should be about 65 again.

    I don't know how they got so low. That's probably what was killing my mpg.
     
  11. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    A half mile drive won't affect your tire pressure much, if at all. At least you know to keep an eye on them now.
     
  12. Cubey

    Cubey Full Access Member

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    I don't know how good my tire gauge is, it's a dually one from O'Reilly with a double sided head. (Xtra Seal 15-1031)

    When I first got it, it was so oily out of the package it was useless because it pushed all the way out. I took it back immediately and teh guy said just try to remove as much of the oil as possible with a paper towel to make it right right.

    I checked the pressures not that many miles ago (about 150?) before I left SD. They seemed ok at that time. They should have all been at 65, not 54 in the front and 70 in the rear. I had left some air out of the rears back when I found out about the 65psi rim thing.

    Both fronts had identical 54psi pressure, so I know it's not a leak in one. I might have let some of the air out due to a bad reading on the tire gauge, I honestly can't remember.

    A review for the gauge on O'Reilly's site says it can read wildly different each reading...

    xtra.jpg
     
  13. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    I have a couple of indentical looking tire gauges. One will gibe the same reading every time. The other will give different ones. If I can ever remember which one it is, I'll throw that one away.
     
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  14. Cubey

    Cubey Full Access Member

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    If you figure out the good one, put a piece of tape on it to remind you so you don't confuse it again if you can't find the screwy one.

    I guess I'll pick up one in another brand from Walmart and see if it's any better/dfferent. They will take back almost anything if you have the package and receipt. The O'Reilly clerk was antsy about the idea of taking it back even though it was 10 minutes later.

    Or even just compare it to my standard style one that goes up to 100psi (which I used on the truck). It wont be able to reach the outer stems very well, but the inner and front would reach.
     
  15. nelstomlinson

    nelstomlinson Full Access Member

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    You keep saying that your rims are marked with a maximum pressure? I've found load and pressure maximums on my tires, but never on my rims. Where should I look on my rims to see what you're talking about?
     

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