What's the correct tire inflation for 31x10.5 ?

[hmdxj]

O.K. I guess the question is clear (Title) and off course I mean on pavement for normal driving and just in case if someone is asking, let’s say we’re talking about BF Goodrich all terrain tires. Don’t be too quick to answer, I’m asking because as I was reading on curing the death wobble problem on kevinsoffroad site ( http://www.kevinsoffroad.com/techarticles/deathwobble.html ) , he mentioned sometime about tire inflation. Here is a quote:

“Another source of Death Wobble is over-inflated tires (you should have around 30psi in stock tires and far less the larger your tires are. See Boyle's Law and consider how much more volume of air you have in your 33" tires compared to stock. I run around 18psi in my 37" tires). “

I must have been sick the day they covered Boyles’ law in school. Or maybe sleeping in class:speepin: . Anyway, the law simply says that as volume increases (Tire size in this case), pressure can decrease, given everything else staying the same.

So, back to the question, given that the original XJ tires are either 225/75-15 or 215/75-15 and their recommended pressure is 33 psi, what would be the correct tire pressure for the 31x10.5 (Or the close equivalent 275/70-R16)?

Note: Assume vehicle weight is stock.

 

[t1snwbrdr12]

ive had 33psi in my 31s for at least 2 or 3 years w/ no problems at all.

 

[dspilot]

Search. I heve seen more than one thread on this lately.

 

[JeepsterSA]

I've had the same question a while back for 30" BFG tyres, and most of the answers varied from 35 - 40 psi which is way too much in my opinion. I'm running my 30" BFG's on 28 psi rear and 30 psi front and no problems at all. Have been running them for about 6 000 km now.

 

[Goatman]

30 lbs is pretty damn close.

I think I ran 30 in my 31's, about 28 in my 32's, don't remember on my 33's, around 23-25 in the 35's, and 18-20 in the 37's.

 

[jdurbach]

Take chaulk or crayon and draw a line across the tire then drive straight for about 100 feet. If the line has worn evenly then you have the proper tire pressure. If it is worn on the outsides and not as much in the middle then you are under inflated. If it wears off more in the middle you are overinflated. This is the test to end the smae discussion from happening over and over again

 

[Goatman]

Search. I heve seen more than one thread on this lately.

This gets old, folks.

 

[dspilot]

This gets old, folks.

So does reading essentially the same thread by a different author each week.

 

[MaXJohnson]

So does reading essentially the same thread by a different author each week.

I knew this guy that hated reading tire inflation threads. I believe he was rocket scientist by trade. Anyway, what he decided to do was to skip over threads that had "tire inflation" in the title.

Try it and see if it works for you.

 

[The Merg]

What, it doesn't say the manufacturer's recommended tire pressure right on the side of the tire?

 

[dspilot]

Now that all of that is out of the way, I run 32 psi in my 30x9.50 BFG ATs, and seems to be fine. I run that on the road and on the trail, and like the handling/driving just fine.

 

[TJ-Shocker]

I run 31 BFG Ta/ko's at 33-35 on the street/highway. If I wheel I usaully take them down to about 13-14. I tried less one trip and bent a wheel pretty good.


I hadn't heard the Crayon trick before, I'll have to try that.

 

[jdurbach]

The grayon trick doesnt lie. Remember the heavier the load the higher the pressure would have to be to achieve even wear

 

[TNT]

What, it doesn't say the manufacturer's recommended tire pressure right on the side of the tire?

It says the manufacturer's maximum recommended tire pressure, not what PSI is need for each different trucks needs.

 

[TheInstaller]

The crayon or chalk trick is the way to go (I prefer chalk). I have 31x10.5's and using the chalk trick came up with 29 psi.

 

[Jeep914x4]

I wet my tire and drove onto dry pavement to check for full tread contact. Same idea as the chalk/crayon.

I put about 28 PSI in my 31's.