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tire pressure

G

Gnat5680

NAXJA Forum User
Location
Bloomington,MN
hey i just got some 30x9.5 LT15 and aired them up to 35 (after i saw an explosion sign on my tire machine) i was wondering if i should air them up to 50 psi like it says on the tire (i think) or what? it is a 6 ply, tire load rating C.

Thanks a lot!
 
Those numbers on the tire (50) are the max. numbers and they are cold numbers as well (the tire heats up from rolling and this effects the psi). I think you would find 50 to be quite a lot of air and thus pretty jaring. I run my 31's at about 25 psi. I was probably somewhere in the low 30's when I was in St. Louis and for whatever reason I tried them lower when I got here and thought it felt better. HTH.

-river
 
Experiment dude. Only then will you find the right psi to "pop wheelies".
 
Gnat5680 said:
so should i just keep it at 35?
Click to expand...
I run the same size tires on my XJ. 35 psi is probably going to be too much air pressure for street use. I run mine at 28 psi in winter & 30 -32 psi the rest of the year. They are wearing very evenly after 2 years.
 
sidriptide said:
yes.......
Click to expand...

SPOBI....I wouldn't go any less than 67.339psi in the left tires and a consistent 52.0000000000000000001 in the rights. (Unless you wanted it to flip over backwards from all the torque).
 
riverfever said:
SPOBI....I wouldn't go any less than 67.339psi in the left tires and a consistent 52.0000000000000000001 in the rights. (Unless you wanted it to flip over backwards from all the torque).
Click to expand...


do you have a daily quota for your post count? :compwork:
 
The best thing to do is use the 4 psi rule. That is you measure them cold and then drive for 15-20 minutes and quickly check one side ( so you can read them faster ) front and rear again. There should be a 4 psi increase in them. If you got less than that you started too high and if you got more than 4 psi you started too low ( too much flex in the side wall ). You may end up with different pressures front to rear as well depening on your load differences over the axle.
 
Does nobody know how to use chalk?

Chalk a line on the tire, drive back and forth in front of your house, adjust pressure until the chalk is worn even.

I wish the max pressure wasn't listed on the sidewall, too many people think that is what they should run.
 
1996cc said:
I wish the max pressure wasn't listed on the sidewall, too many people think that is what they should run.
Click to expand...
:confused1 Don't people read their owner's manuals? Start at that recommend pressure and go down from there.
 
I normally use 30psi, and it works fine, a little bit rough but I think it's around the proper value.

I like 1996cc's idea, I'll try it out some day, but I don't think it will cause a difference of over +/- 3psi from what I have.

Regards
 
Look on the sticker on the inside of the drivers door, it should say what the recomended tire pressure is. Mine is a 99 and it says 33 psi.
 
True guess i didn't think about that. I have 31s and run them around 35 psi. But when i had my stock tires i ran them around the same psi.
 
I recently had a set of new 33x12.5 SSR's installed by Four Wheel Parts... they set the pressure at around 40psi (go figure...). I was wondering why it was handling so squirrelly on the highway and found it was due to the excessive tire pressure, and subsequently, a smaller contact patch. The recommended pressures for a given tire take into account the tire being used on a vehicle that weighs significantly more than an XJ (like a full-size truck, for example). I ended up doing contact patch testing to determine the best pressure and found that about 27psi gives me a full contact patch with these tires. YMMV.
 
The bigger the tyre the less pressure you need for the same weight. This is due that a bigger tyre can hold the same volume of air at a lower pressure.
The chalk line is not a good one either as it does not take into account the rise in pressure that you get once driving.
 
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