Proper Tire Inflation

[Blue88Comanche]

As the title says, What is the proper tire inflation pressure for 31x10.5 R15 tires for our MJs? Currently I think they are at 30 PSI.

[Alexia]

As the title says, What is the proper tire inflation pressure for 31x10.5 R15 tires for our MJs? Currently I think they are at 30 PSI.

 

Depends on the tire and such. I prefer around 25 PSI, but heavier loads require more PSI for the best tire contact.

[Blue88Comanche]

i have General Grabber AT2. Is there some method to find the ideal pressure? I don't tow or haul with it often and the last "heavy" load was a trailer with 1000 lbs of gravel.

[Eagle]

28 to 30 is good.

[cruiser54]

28 to 30 is good.

 

Works great.

[skidoo_j]

i have General Grabber AT2. Is there some method to find the ideal pressure? I don't tow or haul with it often and the last "heavy" load was a trailer with 1000 lbs of gravel.

 

 

You want enough air to prevent cupping which will cause wear on the outside of tread. However you don't want too much pressure as it could cause the center of the tread to bulge out causing wear in the center of the tread.

 

Even through I have 31/1050's I still use the factory air pressure of 33 ish psi. I use this because I've not noticed any issues with odd tread wear. 30 psi is going to be right in there too.

 

Do not however read an article about using the ideal gas law to determine you need lower pressure in larger tires. The argument the company makes is incorrect as the ideal gas law assumes a sealed container where more molecules of air cannot be added. Therefore bigger tires do not mean you need to run less air pressure.

 

 

With that said this is for on-road-driving. In an off road scenario people with beadlocks can run only 2-3psi iirc. I do not have beadlocks, and if going off road will air down to about 20 psi.

[dave92cherokee]

Figure out the optimal pressure for your tires instead of what works in someone else's tires. Get some sidewalk chalk and draw 2-3 lines across the entire tread of each tire. Then move it back and fourth a few times then look to see where the chalk's been rubbed off at. If it's rubbed off inside but not outside deflate some, and if it's rubbed off outside but not inside inflate some. Then re-run the test until it rubs off evenly.

[HOrnbrod]

Figure out the optimal pressure for your tires instead of what works in someone else's tires. Get some sidewalk chalk and draw 2-3 lines across the entire tread of each tire. Then move it back and fourth a few times then look to see where the chalk's been rubbed off at. If it's rubbed off inside but not outside deflate some, and if it's rubbed off outside but not inside inflate some. Then re-run the test until it rubs off evenly.

 

:agree: With my 31" Michelins using a similar method it works out to 30 PSI front, 25 PSI rear. With a load I air up the rears to 30 PSI or more. And don't forget to rotate every 3K-5K miles. :D

[skidoo_j]

Figure out the optimal pressure for your tires instead of what works in someone else's tires. Get some sidewalk chalk and draw 2-3 lines across the entire tread of each tire. Then move it back and fourth a few times then look to see where the chalk's been rubbed off at. If it's rubbed off inside but not outside deflate some, and if it's rubbed off outside but not inside inflate some. Then re-run the test until it rubs off evenly.

 

 

Using side walk chalk is pretty smart. I've done it with chalk line chalk and coun't tell a damn thing cuz it went everywhere.