I just went and checked the tire pressure in my XJ for the first time. (I've only driven it about 300 miles) All of them were between 35 and 40 PSI. On the side of the tire it says "Max load 1990 lbs at 50 PSI cold". Doesn't specifically say that the recommended pressure is 50psi though. Does that sound a little high to anyone else?
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50 PSI tire pressure??
- Thread starter ZmOz
- Start date
- Location
- Terra Firma
What size tires do you have?
The recommended pressure for stock tires is 30 psi. That 50 psi is the pressure you need to run in that tire IF you plan to overload the vehicle and carry enough weight that your vehicle weighs in at 7960 pounds (1990 x 4).
If you run oversize tires, there is no reason to run pressure higher than the 30 psi for stock tires, and in most cases the correct pressure for a larger tire should be less than the pressure for a stock tire.
The recommended pressure for stock tires is 30 psi. That 50 psi is the pressure you need to run in that tire IF you plan to overload the vehicle and carry enough weight that your vehicle weighs in at 7960 pounds (1990 x 4).
If you run oversize tires, there is no reason to run pressure higher than the 30 psi for stock tires, and in most cases the correct pressure for a larger tire should be less than the pressure for a stock tire.
h.curtis
NAXJA Forum User
- Location
- Pittsburgh, PA
ZmOz said:These are 30x9.5 tires. Shouldn't it say somewhere what normal pressure would be??
No, tire pressure recommendations are in the vehicle's manual, not on the tire. All vehicles are different. I run 28 pounds in my Jeep because I have 31's. With 30's you may want to run 30 or so.
Curt
2xtreme
NAXJA Forum User
- Location
- Kayak Pt, WA
recommended tire pressures are never (normal dot tires) written on the tire, only the max load tire pressure. The tire pressure that you run in a tire should depend on the vehicle that the tire is on, due to weight of vehicle and position of tire, etc.
Usually I run between 30 and 35 psi in my tires. but tire wear is the best judge of what pressure you should run and obviouly that can change if you are carrying heavier loads.
Michael
Usually I run between 30 and 35 psi in my tires. but tire wear is the best judge of what pressure you should run and obviouly that can change if you are carrying heavier loads.
Michael
- Location
- Terra Firma
2xtreme said:
Exactly. The pressure you see on the sidewall of any tire is not a recommended operating pressure, it is a maximum pressure for maximum load conditions.
The owner's manual gives recommended pressures for several tire sizes. If you choose a tire that's not one of the sizes listed, it becomes your responsibility to determine the correct operating pressure.
- Location
- Colorado Springs, CO
It's the pressure you would inflate the tire to when cold, if the load on that tire were the stated maximum load.
As you said, if he were to load his tire to 1990 pounds, or all four to 7960 pounds, than he would have to inflate his tire or tires to 50 psi(or is it 50 psia?) when cold.
A little different than maximum pressure for maximum load.
Cranky because I'm not in Utah.
Fred
As you said, if he were to load his tire to 1990 pounds, or all four to 7960 pounds, than he would have to inflate his tire or tires to 50 psi(or is it 50 psia?
) when cold.A little different than maximum pressure for maximum load.
Cranky because I'm not in Utah.
Fred
- Location
- Terra Firma
Fred said:It's the pressure you would inflate the tire to when cold, if the load on that tire were the stated maximum load.
As you said, if he were to load his tire to 1990 pounds, or all four to 7960 pounds, than he would have to inflate his tire or tires to 50 psi(or is it 50 psia?
A little different than maximum pressure for maximum load.
Cranky because I'm not in Utah.
Fred
Semantics, Amigo --
I think we're on the same team here. Yes, 50 psi is the correct pressure for a maximum loading on that tire of 1990 pounds. But why is 1990 pounds the maximum load? Because it requires 50 psi to support it, and that tire isn't safe to inflate beyond 50 psi. That's way I said it's a maximum pressure for a maximum load.
FWIW, 50 psi is a very high max pressure. That's definitely a light truck tire. IIRC most passenger tires have a max pressure of 32 psi or 36 psi.
vintagespeed
NAXJA Forum User
- Location
- Upland, CA
My F250's tires are rated at a maximum of 90psi! Never saw air pressure that high before on a tire.
Karlm
NAXJA Forum User
- Location
- Antioch, CA
Lots of really old tires run pressures that high. I'm talking like Model Ts and things from that era. IIRC the last time I swapped out a tire on a T it was somewhere in the 60-90 psi range.
- Location
- Terra Firma
Karlm said:
Sure, but those were essentially bicycle tires. Bike tires still run at 60 psi and higher.
Flyfisher
NAXJA Forum User
- Location
- Billings, Montana
OK...here's the straight-skinny. The stock tire size and pressure are on a sticker onthe door. Open the door...look at the back of the drivers door..it lists the stock tire size and pressure.
For oversized tires...I'd agree with prior posts....nothing more, probably a few pounds less.
I run 31x10.50's and run 30 psi for daily use. I usually air down to 15 psi for off-road use...then air back up again before exceeding 30 mph.
Flyfisher
For oversized tires...I'd agree with prior posts....nothing more, probably a few pounds less.
I run 31x10.50's and run 30 psi for daily use. I usually air down to 15 psi for off-road use...then air back up again before exceeding 30 mph.
Flyfisher
RCP Phx
NAXJA Forum User
- Location
- Phoenix,Az
XJguy said:
Thats more likely caused by your lift height and control arm angles!
jjvande
NAXJA Forum User
- Location
- Albuquerque NM 505 burque
in the case of tires. its psia or psi.
h.curtis
NAXJA Forum User
- Location
- Pittsburgh, PA
RCP Phx said:
I can't agree here. XJ's are only around 3000 pounds. He is running 35's on it. Those tires are overkill for the XJ and you must run lower pressure unless you want to ride on the center of the tire only. If he was running 30 psi in them they would be like rocks for that light vehicle. Too much tire for the XJ, but we want the ground clearance, so we run them with low pressure.
JMHO,
Curt