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different tire PSI front and rear or same?

2001XJ

2001XJ

NAXJA Forum User
Location
Canton, MI
Have done the search, have read about the 4 PSI and white mark across the tread techniques but no specific answers to my question. Do you guys run different PSI in the front and rear tires or just the same PSI all around? I figured the PSI in the front should be higher due to the weight of the engine but not sure. It is a daily driver with offroad on the weekends but not all the time so I am trying to prolong the life of my tires. I used the 4 psi technique and have been running my brand new BFG AT 32x11.5's with 43PSI in the front and 37PSI in the rear. Tread seems to be wearing evenly and rides good. Should I do something differently?

thanks
 
on 33's I ran at like 28-30psi...

now that im on 35's, it lives at 11psi :D
 
when i got them back from the tire shop they said they set them to manf. specs which was 35PSI. I looked at them though and the side wall was bulging kinda good so I decided to try the 4 psi rule and ended up setting them at 43 which gave me an increase up to 47 when driven for about 20 minutes and made the side walls better looking. Did the same in the rear but got the 4 psi increase when they were set to 37psi.
 
mecompco said:
I run my 235s at 32 psi front and rear. Rotate every 3K. Very even wear and comfortable ride.
Click to expand...

so there is not need to accomodate for the heavier load in the front?
 
I run 28 normally, bump it up to 33 if I'm going on a long highway trip.

47 is too freaking high. Radials are supposed to bulge.
 
guess I am airing down. The concensus for sure is to run uniform tire pressure all around though? Yeah, I know radials are supposed to bulge but they were bulging too much it seemed....like a semi flat tire...didn't think they were supposed to buldge that much
 
2001XJ said:
guess I am airing down. The concensus for sure is to run uniform tire pressure all around though? Yeah, I know radials are supposed to bulge but they were bulging too much it seemed....like a semi flat tire...didn't think they were supposed to buldge that much
Click to expand...


As long as the sidewall is not on the pavement, its good.

Most people run the same PSI front/rear. I suppose you could run a little more up front, but I cant imagine any reason to. I run even PSI and get even wear.

If you are that worried about it, take a couple pictures of it at 30 psi and post them up.
 
I've run my bias-ply Swampers at different psi on the trail only, 6 in the front, 5 in the rear. I keep them all at 25 on the road.
 
32x11.5 AT's I run them at 35. I use to run them at 32, but I like them better at 35.

When I first got them the person who inflated them must have been high or something. Two of them were around 44, one was in the 30's range, and I can't remember what the last one was. I was driving down a bumpy dirt road and I could feel everything,and the tool chest I had in back was rattling, then when got out my gage, set them down to 32 and it was much smoother and almost no rattle.

I won't mention the time I almost blew up my brother's 30 inch tire when I wasn't paying attention inflating it after the beach. Man I was surprised to see 50 on that gage.
 
don't forget that you're current load will also determine your tire pressures.
The road tires in the MJ are set at 32PSI front, and 28 PSI rear, when the bed isn't loaded.

When I have the bed full of gear and crap I put 45 in the rears.
Find out your tires maximum load rating, that load rating will be at maximum tire pressure. Now, guestimate how much weight is on each tire, and vary the PSI proportional to the max. That will give you a good starting point.
 
87manche said:
don't forget that you're current load will also determine your tire pressures.
The road tires in the MJ are set at 32PSI front, and 28 PSI rear, when the bed isn't loaded.

When I have the bed full of gear and crap I put 45 in the rears.
Find out your tires maximum load rating, that load rating will be at maximum tire pressure. Now, guestimate how much weight is on each tire, and vary the PSI proportional to the max. That will give you a good starting point.
Click to expand...

This is what my original question was....if it is needed to run different PSI in front and rear for loads. IE> engine in front so front tires are set a little higher. Don't know if it makes that much of a difference or is needed. I never have the rear loaded extremely heavy although I do have the full spare mounted on the rear bumper. Again, seems like it's getting really nit picky but was curious.
 
i have 33x12.5 BFG mud terrains and i have 20psi in the front and 22psi in the rear. i air up the tires and then let it out until the edge of the tire almost meets the concrete. (same idea as the chalk/marker rule?)

43psi is super high i think.

btw, what is the 4psi thing?
 
330LICIOUS said:
btw, what is the 4psi thing?
Click to expand...

Compliments of GoJeep:

You take your pressures front and rear cold and then go for a drive for about 20 minutes. Then jump out and quickly take the pressure again down one side and if you have the right starting pressure, they should have gone up 4 psi. If is has gone up more it means the tyre is flexing too much and generating excess heat so raise the starting pressure a few psi and start again. If it goes up less it means you started too high.
 
2001XJ said:
This is what my original question was....if it is needed to run different PSI in front and rear for loads. IE> engine in front so front tires are set a little higher. Don't know if it makes that much of a difference or is needed. I never have the rear loaded extremely heavy although I do have the full spare mounted on the rear bumper. Again, seems like it's getting really nit picky but was curious.
Click to expand...
well, that's something you need to consider.
When unloaded the MJ is probably a lot lighter than your XJ in the rear. So 32 PSI of air makes the back end a bit squirelly, and ride really harsh.
On that same token, if I kep it at 28 and toss 1K lbs of gear in the back it get's darty, because the sidewalls are flexing enough to affect handling.

The 4 PSI thing is a very good start. I would imagine XJ's would run the same front and rear simply because it's more evenly distributed. THe MJ is very front heavy when unloaded.
 
I have BFG 32's, and am currently running 30#. They had a lot more pressure than that when installed by the tire shop, so I kept trying the 4 PSI rule until I got down to 30#. I haven't checked again since then to see if I need to go lower or not, but I'm sure that they are very close.
 
I can't believe you run over 35 psi in your tires!! H0w does that ride??

I usually run about 1-2 psi high in the front than the rear, due to the motor and such. On the road I ran my 31s and run my 32s at around 30 psi give or take a few depending on conditions, temp, and my mood. I wouldn't go much higher than that tough.

I see a lot of people with BFG ATs that run them at too high of pressure, as evidenced by the center of the tread being worn out and the outer edges still having some tread life left.
 
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