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What is the correct tire pressure if you have oversized tires. I have 265's with a max of 44 psi. Wrangler calls for 30 psi on stock tires. So.....?
 

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This is from an old thread on a different forum, pretty accurate as far as I know:

Take the max weight that the tire can support (on sidewall) and multiply that by 4. This gives you the total weight that all four tires can support. Next take the weight of your jeep and divide that into the total weight. You should get around 1.8-2 something. Now divide this number into the max psi stated on teh sidewall and you'll have your ideal air pressure. most 31" or taller tires can support light-truck weighted applications and jeeps are just too light, requiring only 1/2 of the max psi.

For instance:

2000 lbs at 50 psi max

2000 x 4 = 8000

My 4 cyl's jeep weight with add-ons: 3800 lbs

8000 / 3800 = 2.1

50/2.1 = 23.8 psi

It's best to set the front tires a little higher due to the engine weight.
25 front 23-24 rear



And there's always the chalk test:

Take a guess at a PSI for your tires (usually larger tires require less PSI), run a thick line of chalk horizontally across the tread. Drive a few yards to let the chalk line touch the ground several times. Then look at the chalk line and read the results:

1) more wear on the middle of the tire = too much air pressure
2) more wear on the outside of the tire = too low pressure
3) even wear across tread = good pressure
 

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What is the correct tire pressure if you have oversized tires. I have 265's with a max of 44 psi. Wrangler calls for 30 psi on stock tires. So.....?
265 what, we need the full size number to give you a starting point.
Max pressure is just what it says, not the running pressure.
 

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Discussion Starter · #6 ·
sparky said:
265 what, we need the full size number to give you a starting point.
Max pressure is just what it says, not the running pressure.
265 75 16
 

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The tire itself should tell you. Look on the wall of the tire it will have its size and recommended tire pressure
While many inflate their tires to that pressure, doing so is never correct for an automotive application. The air pressure molded onto a tire's sidewall is only its maximum safe air pressure which is only to be used when the tire is carrying its maximum safe weight. Vehicle tires never carry their maximum safe weight, most carry around 50% of the tire's max safe limit.

The correct air pressure depends entirely on the weight the tire is supporting. The correct air pressure, for example, in a 33x12.50 Goodyear MT/R carrying a Wrangler TJ would not be enough if that same exact tire was supporting a much heavier truck.

In other words, it is never correct to inflate a tire supporting a Jeep to the pressure indicated on the tire's sidewall. And don't feel like the lone stranger on this... even many tire store employees don't understand this and often erroneously inflate tires to the psi indicated on the sidewall. :)
 

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I agree with Jerry. I work in a tire/auto shop and when we do tires we take into consideration what the customer uses the vehicle for and the load/speed rating of the tires. I have E rated tires on my jeep. On something as light as a jeep is, the max tire pressure would be a terrible ride. I played around with pressures when I first put them on and I found 28 psi ideal.
 

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Three of our tires were severely overinflated (45 psi - sidewall says 40 is max) and caused crazy uneven wear. Now I know to always check the tires after a shop has checked them. After decreasing PSI to 32, our LJ's highway vibration seems worse. Handles better though, particularly when braking and cornering. Grips the road real well. I know we have a loose trackbar bushing that 'knocks' the steering wheel, causes some of the vibration. I also suspect the tires need balancing. But my questions for this thread: 1) Will the tires begin to even out as we drive at this lower psi? 2) How much of our vibration problem do you think could be contributed to the uneven wear in the tires caused by incorrect psi?
 

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I go by how the tires look, how the Jeep is handling and the mpg. I typically put in about 30 psi in my Goodyear Wrangler tires.
 

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That's a JK question & I believe the dealer can reprogram for you. Get them to check it while in for another service & you might be able to get it done for free'ish.
 

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I have the AT3 as well and find them to be a very stiff sidewalk making for an ever rougher ride. I have been running them at 25 psi all summer and I think it's fine.
I did read a warning from Cooper that you should check the air pressure to make sure that they haven't gone flat.
Sure enough at one point my steering was a little off and I checked the air pressure and found 0 psi in front passenger. Took it to shop and they found a little corrosion on the rim causing slow leak.
There was no difference visually between the inflated and flat tire.
 

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^^^^^ the joys of running a heavy E Rated tire on a light TJ... run flat capabilities.
 
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