wrong tires type :(

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I went and get my tires balance and rotation today, ready for 24 hours round trip, the guy came in and say your truck having wrong tires. The factory tires for my truck is P265/70R17 35PSI front and rear

now the tires on the truck now is LT 265/70R17 , and the guy that install my tires say this tires is for HD 2500+ truck.

Now Im confused about PSI rate, some word on tires say 80PSI max, and some where on there say never exceed 40psi.

he put 35 psi on it right now, but when I bought this truck I check the pressure and its 46psi.

I been running 35psi for about 3 month now. gas miles still the same, run smooth on highway..
 
That sounds about right, you have the 2500 tires, which carry a higher load rating for that comes with the 2500.

When putting air pressure in the tire you should go by the door jam which tells you what PSI you need to go with the oem size. 35 psi sounds correct.
 
You have LT-rated (Light Truck) tires instead of P-metric (passenger series) tires. The size is the same, so you don't have "the wrong tire." LT rated tires just are made "beefier" with more plies in the tread and stiffer sidewalls. They ride rougher, don't handle quite as well, but take more abuse without damage and have a higher load rating (typically). If you ever go offroad, LT tires are an advantage because they are less susceptible to sidewall punctures. For a working truck, I would prefer LT tires. For a highway vehicle that never operates near maximum load, then P-series would pay off in better ride and handling. Your call.

Follow the pressure on the VEHICLE (usually there's a tire pressure placard in the driver's door jamb or on the end of the door itself), not the tire. Check and change the pressure with the tires COLD, not hot.
 
In a way, yes, they're the wrong tires. But they're still very much usable.

They don't need 80 psi in them, unless you're hauling heavy loads.

But 35 psi likely isn't enough. The 46 psi that they had in them when you bought the truck is probably closer to what you need, than either 35 psi or 80 psi.

There's a formula to determine a good psi for you. I used it once and don't want to use it again. Someone will chime in, maybe CapriRacer will stroll through here soon.
 
so I should stay with 35psi even its wrong type of rating tires ?

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Originally Posted By: 901Memphis
When putting air pressure in the tire you should go by the door jam which tells you what PSI you need to go with the oem size. 35 psi sounds correct.


I don't think you've got this right. The vehicle calls for "P" and he has "LT" installed. Therefore, the figure on the door jamb is wrong, as there's a different tire installed on the vehicle.
 
Originally Posted By: MetalSlug
so I should stay with 35psi even its wrong type of rating tires ?


35psi is not right.
 
As stated above, you basically have the correct size tire, but they are a heavier duty construction than the original P-Metric tires. Check the placard on the inside of the driver's door. It should give you the recommended tire inflation pressure for LT-Metric tires.
 
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Originally Posted By: knerml
As stated above, you basically have the correct size tire, but they are a heavier duty construction than the original P-Metric tires. Check the placard on the inside of the driver's door. It should give you the recommended tire inflation pressure for LT-Metric tires.


I dont have LT rate

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Originally Posted By: MetalSlug


Now Im confused about PSI rate, some word on tires say 80PSI max, and some where on there say never exceed 40psi.



The warning about the 40 psi may the max pressure to seat the beads, not max inflation pressure
 
Originally Posted By: MetalSlug
ok now im clueless


This is why the previous owner didn't do you any favors when he put the LT-rated tires on, instead of the proper P-rated tire.
 
Go by the door jamb. In this case, 35 PSI. Those tires might need 50 PSI on a stake-bed commercial truck. Not on your Expedition. Whether it has P-metric or LT series tires, 35 PSI (cold) is the correct inflation pressure so long as the size of the tire is the same, as in this case. The pressure is related to the load and the size of the contact patch. Over-inflating "just because you have LT tires now" will degrade handling, maybe even to the point of being unsafe.
 
Originally Posted By: 440Magnum
Go by the door jamb. In this case, 35 PSI. Those tires might need 50 PSI on a stake-bed commercial truck. Not on your Expedition. Whether it has P-metric or LT series tires, 35 PSI (cold) is the correct inflation pressure so long as the size of the tire is the same, as in this case. The pressure is related to the load and the size of the contact patch. Over-inflating "just because you have LT tires now" will degrade handling, maybe even to the point of being unsafe.





Wrong, wrong, wrong. Plain and simple. Please stop sharing "advice" like this.

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35psi sounds too low. I'd want to check tire temp after driving for 30min plus. If it's hot, it's too low.

Absolute wild guess here but I'd assume that the tire pressure for the same size tire on an F250 is probably close, assuming again that it's an LT tire. Similar weights and all.

40psi is the max to seat the beads. LT tires run higher pressures than that. But you wouldn't want the tire at 80psi trying to get the bead to "pop" into place.

Have you done a search on google? Perhaps there are other Expedition owners who have decided to run LT tires, and have done the leg work on a suggested tire pressure.
 
Originally Posted By: mrsilv04
Originally Posted By: 440Magnum
Go by the door jamb. In this case, 35 PSI. Those tires might need 50 PSI on a stake-bed commercial truck. Not on your Expedition. Whether it has P-metric or LT series tires, 35 PSI (cold) is the correct inflation pressure so long as the size of the tire is the same, as in this case. The pressure is related to the load and the size of the contact patch. Over-inflating "just because you have LT tires now" will degrade handling, maybe even to the point of being unsafe.





Wrong, wrong, wrong. Plain and simple. Please stop sharing "advice" like this.

Snip_zps4fb529ed.jpg




BINGO! There is, as noted, a formula to determine the correct pressure and 35psi for an LT tire isn't it. It is probably in the mid to high 40's IIRC.
 
I just call tireack.com lol, I know i know, I explaint him the situation, about the P and the LT , he say if you carry heavy load hauling heavy load run 5-10 psi above the door jam ( 35 psi ), and I told him i just carry peoples, he say still run 35psi.

Right now im running 40psi, I will try to pump up 43 for this trip.
 
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35psi is too low, LT tires need more PSI to carry the same weight as a P-metric.

I'd start at about 45psi empty, but someone smarter than me can find the load table and give you the correct pressures.
 
Here's a document from Yokohama:

http://www.yokohamatire.com/assets/docs/tsb_070302.pdf

Quote:
To replace P235/75R15 size tires on a vehicle, with this size shown on the
placard as the original equipment size with 35 psi inflation, two LT sizes
are acceptable providing that 15 psi is added to the inflation pressure.
From the table, the LT235/75R15(C) and 30x9.50R15(C) sizes are
acceptable at 50 psi. 35 psi is not acceptable in either of the replacement
tire sizes.


Just looking at the table (which doesn't list your exact size) you should be adding 15PSI to the base 35psi on your door jamb. So you should be running 50psi in the LT tires.
 
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