# Tire Pressure on 1998 Dodge

• posted on October 18, 2006, 11:03 pm
Hello All,
I bought a 1998 Dodge Ram 1500 4X4 Quad Cab recently. Which came with LT 285 75R16 All Terrain T/A KO tires, after driving for a couple of months
I noticed tires looked low. When I had the oil changed I asked them to check the tire pressure. They told me that my tires where properly inflated at 35 PSI. I went by local tire company to have them checked again as they still looked low. The guy there told me he added 2 PSI to each front tire back rears were fine. Tires actually say 65 PSI. When I questioned him about this he told me they were fine. I understand that the Door Panel of the truck says 35-40 PSI, however these are not original tires, they are oversized. Could someone shed some light here?

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• posted on October 18, 2006, 11:16 pm
Gina Fierro wrote:

This can be a difficult problem. The best gauge of proper tire pressure is tread wear. But if you guess wrong, you'll wear out the tires too soon.
You already know these are not stock tires, and you know the sticker in the door frame is useless. They are heavy duty truck tires, designed to carry a maximum load. Look on the sidewall, and you'll see lettering that says Xpsi at Y pounds. Calculate how much of a load your tires do have, and devide by 4. That's about how much weight is on each tire. Now look at what your max tire pressure is. Whatever the percentage of max load you have, that's the percentage of tire pressure you should start with.
That is a pretty crude calculation because it doesn't include front to rer bias, cross weights, etc. But it will get you in the ball park.
Now go drive the truck for a while. Long enough to get the tires good and warm. Use an infrared thermometer and check the tire temp in the middle and ech side of the tread. Should be roughly equal when the pressure is right.
If you don't have a thermometer, you can use the chalk/paint method. Not nearly as accurate but a whole lot cheaper and probably close enough. After the tires are warm, put some paint or chalk across the tread. Roll foreward just a few tire rotations. You can see where the chalk/paint is scuffed off. Again, should be equal across the tread pattern when the pressure is right.
--
.boB
Arrived: 2006 FXDI, Red.

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• posted on October 18, 2006, 11:34 pm

So, it's ok to run 65 PSI with stock rims? I'd have guessed that 65 psi would be too much.

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• posted on October 19, 2006, 1:58 am

No, it is not. If that is the max pressure on the sidewall and you are carrying no load.
Roy

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• posted on October 19, 2006, 2:49 am

65 psi is way high for a 1/2 ton truck. to load a tire heavy enough to require 65 psi for the profile to be right you more than likely have overloaded the truck.
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-Chris

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• posted on October 19, 2006, 3:44 am

Well, yes and no. The stock rims will handle tire pressures of 65psi, and probably more. They are pretty sturdy. However, take a look again at the weight rating on the tire. Look at how much weight the tires have to be carrying to reach their max. Probably far more than your truck can carry safely. That means - as far as the tires are concerned - you have a huge safety margin in weight capacity.
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.boB
Arrived: 2006 FXDI, Red.

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• posted on October 20, 2006, 5:23 pm

If there is no weight in the back of the truck while running the tires that hard, the stopping didstance will be much longer. Roy