What tire psi
09-25-2011, 07:39 PM
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Year: 2000
Model: Cherokee
Engine: 4.0
What tire psi
I have a 2000 xj, and i am running a 15x8 inch rim with 32x11.5 inch tires most of the time it is driven on the street. What psi should I be running for even wear? Thanks
09-26-2011, 06:15 AM
#3
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It's dependent alot upon vehicle weight, and the load rating of your tires. I run my 33x12.5 Duratracs at 28 in the front and 26 in the rear (a lot less weight back there, I'm never loaded down with cargo.) General consensus is somewhere around 30PSI. I just adjusted mine until the tread width had full contact with the ground.
09-26-2011, 07:30 AM
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Year: 1998
Model: Cherokee
Engine: 4.0 stock
It will depend if you have a radial or a bias ply tire... you told us the size but not the type.
I have 15X8 with 32X11.5X15 radial... since it isn't the factory tire a lot of factors will come into play... Higher weight rating and a sidewall that has more ply than the stock tire might make higher PSI ride rough... However since it is a radial I still go with what is on the sticker on the driver door which is 32 PSI.
I have 15X8 with 32X11.5X15 radial... since it isn't the factory tire a lot of factors will come into play... Higher weight rating and a sidewall that has more ply than the stock tire might make higher PSI ride rough... However since it is a radial I still go with what is on the sticker on the driver door which is 32 PSI.
09-26-2011, 09:22 AM
#5
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What are you putting in the tires, air or nitrogen? If air, keep it around 33, if nitrogen, go up to 42. ALWAYS refer to manufacturer specs. If your tire calls for a max of 44PSI and youre putting air in them, drop that by 10 because air expands when its hot due to moisture content whereas nitrogen will not. If you put 44PSI of air in a tire that calls for a max of 44PSI, then take a trip on a hot day or down the highway an hour or more, youre tire could be up to 54PSI and thats SUPER dangerous.
Last edited by bigvig; 09-26-2011 at 11:00 AM.
09-26-2011, 09:27 AM
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Year: 1998
Model: Cherokee
Engine: 4.0 stock
The rating on the tire is it's maximum pressure for it's maximum load rating.
If you have a tire that is rated for 8,000lbs at a max pressure of 50PSI, Then you inflate the tire to 50PSI but the vehicle only weighs 4,000 lbs you will have the inside of the tire wear faster than the outside because there is not enough weight on that tire. Always follow the PSI suggested in a vehicle's owner's manual and or the sticker on the driver's door jam.
If you have a tire that is rated for 8,000lbs at a max pressure of 50PSI, Then you inflate the tire to 50PSI but the vehicle only weighs 4,000 lbs you will have the inside of the tire wear faster than the outside because there is not enough weight on that tire. Always follow the PSI suggested in a vehicle's owner's manual and or the sticker on the driver's door jam.
09-26-2011, 11:26 AM
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Year: 1997
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The rating on the tire is it's maximum pressure for it's maximum load rating.
If you have a tire that is rated for 8,000lbs at a max pressure of 50PSI, Then you inflate the tire to 50PSI but the vehicle only weighs 4,000 lbs you will have the inside of the tire wear faster than the outside because there is not enough weight on that tire. Always follow the PSI suggested in a vehicle's owner's manual and or the sticker on the driver's door jam.
If you have a tire that is rated for 8,000lbs at a max pressure of 50PSI, Then you inflate the tire to 50PSI but the vehicle only weighs 4,000 lbs you will have the inside of the tire wear faster than the outside because there is not enough weight on that tire. Always follow the PSI suggested in a vehicle's owner's manual and or the sticker on the driver's door jam.
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09-26-2011, 01:26 PM
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Year: 1993
Model: Cherokee
Engine: 4.0
The PSI recommended on the door jam is for a stock weight vehicle with the stock size tires.
My Cherokee weighs a little under 4000 lbs and I'm running 35x12.5 r15s with 20 psi. If I decide to drive it somewhere over 100 miles one way I'll probably increase the pressure to 24 psi, but most of my driving is less than 50 miles one way.
My Cherokee weighs a little under 4000 lbs and I'm running 35x12.5 r15s with 20 psi. If I decide to drive it somewhere over 100 miles one way I'll probably increase the pressure to 24 psi, but most of my driving is less than 50 miles one way.
09-26-2011, 01:40 PM
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Year: 1998
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I dug this up with google...
http://www.jeepcommander.com/forums/...hp/t-2940.html
http://www.jeepcommander.com/forums/...hp/t-2940.html
Originally Posted by XHCommander
The recommended pressures listed in the vehicle's placard are ok for stock tyres but larger tires handle your vehicle's weight differently than stock and thus the original placard recommendations don't necessarily apply.
When your Jeep is loaded up these are methods I know of:
1) The Chalk/Crayon Method.
"Make a mark all the way across each tire.
Drive the Jeep for a short distance, a straight line is best.
Note the wear pattern in the chalk. If there is chalk left at the edge the tire is over inflated.
Chalk left in the center means it's under-inflated.
A clean pattern indicates the pressure is just right.
Make a note of the pressure for future reference.
This procedure would need to be performed again of different size or style tires are added"
2) Muddeprived's Method
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 the 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
3) Footprint Method
For loaded vehicles, weight should vary little from empty to fully loaded on the front axle if the load is evenly distributed. Start with the tyres at their Ideal load Pressure (empty) and measure tyre tread length (tyre footprint) before packing. After loading, tyre pressures may need adjusting to get the same length at both the back and front.
The tyre footprint can be measured by placing a straight edge at the front and rear of the tyre where it meets the road surface. Simply measure between these two reference points.
4) The Load Ratio Method
For vehicles with load not equally distributed over each axle, the front and rear tyre pressures can be determined using the axle load distribution ratio
Example:
If front to rear load distribution of the vehicle is 40:60:
Front Pressure = (40/50) x Ideal Load Pressure
Rear Pressure = (60/50) x Ideal Load Pressure
Assume: Ideal Load Pressure = 33psi (loaded)
Therefore: Front Pressure = 40÷50x33 = 26psi
& Rear Pressure = 60÷50x33 = 39psi
What is the Ideal Load Pressure?? Try Muddeprived's method: http://www.jeepforum.com/forum/f13/h...75/index2.html
And there are others...The 4psi rule is easy and works.
When your Jeep is loaded up these are methods I know of:
1) The Chalk/Crayon Method.
"Make a mark all the way across each tire.
Drive the Jeep for a short distance, a straight line is best.
Note the wear pattern in the chalk. If there is chalk left at the edge the tire is over inflated.
Chalk left in the center means it's under-inflated.
A clean pattern indicates the pressure is just right.
Make a note of the pressure for future reference.
This procedure would need to be performed again of different size or style tires are added"
2) Muddeprived's Method
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 the 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
3) Footprint Method
For loaded vehicles, weight should vary little from empty to fully loaded on the front axle if the load is evenly distributed. Start with the tyres at their Ideal load Pressure (empty) and measure tyre tread length (tyre footprint) before packing. After loading, tyre pressures may need adjusting to get the same length at both the back and front.
The tyre footprint can be measured by placing a straight edge at the front and rear of the tyre where it meets the road surface. Simply measure between these two reference points.
4) The Load Ratio Method
For vehicles with load not equally distributed over each axle, the front and rear tyre pressures can be determined using the axle load distribution ratio
Example:
If front to rear load distribution of the vehicle is 40:60:
Front Pressure = (40/50) x Ideal Load Pressure
Rear Pressure = (60/50) x Ideal Load Pressure
Assume: Ideal Load Pressure = 33psi (loaded)
Therefore: Front Pressure = 40÷50x33 = 26psi
& Rear Pressure = 60÷50x33 = 39psi
What is the Ideal Load Pressure?? Try Muddeprived's method: http://www.jeepforum.com/forum/f13/h...75/index2.html
And there are others...The 4psi rule is easy and works.
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