40below

Hey all, I am going on a long road trip in the months ahead and in my preparation I would like to know how to check tire pressure. I seen on youtube that you can get the exact tire pressure or psi on the drivers door. Where can I get a psi checker for a low price and any suggestions on how to check the pressure. May sound funny but I never done this before and want to be fully prepared for the road ahead of me especially with my wife and kids with me. Thanks!

Addy

Here is a picture of a pretty basic gauge


Pretty much anywhere will sell them. Go to a Wal-mart or something and just ask an associate where they are. If you don't have a Wal-mart like store anywhere, every auto-motive store on the entire planet will have them for sale. Should cost maybe 6$, tops.

You'll twist the little cap off on your tire (near the outside of the rim) and insert the gauge firmly to get your psi reading. If you're under what's needed (going to assume 33-35 is what your driver door is going to tell you), you're going to need to visit a gas station and use their air hose. I'm, again, assuming that you do not have an air compressor in your garage.

And after you get done, keep that guage in your glovebox or something, should always have one with you

40below

Thanks Addy!!!

Eva

Use the PSI rating on the outer wall of your tire, not the one on your door. Each tire requires different air pressure, and you need to match the pressure to the tire.

tiwvr1

Eva you have to be joking! The pressure on the sidewall of your tire is max pressure. Do not ever go by that. Go buy what the vehical calls for. I work at a tire shop and can't STAND people that believe u put in what the tire calls for on the side wall. That is why on the sidewall it says MAX pressure. Your tires sidewall doesn't know what your vehical weighs.

Addy

That pressure is for when the tire is under load, or heated and has been running. Air will expand in the tire as you raise the energy in the system, creating faster molecular movement and causing it to expand, creating higher pressure. You don't ever want to be at that pressure while cold.

Edit: But you do raise a good point. If your tire's are not what is recommended on that door label, iirc p225, then the suggested pressure means nothing.

muddpigg

35 - 40 is just fine, unless your tires are LT (light truck) designated - and then it's still just a grand cherokee not a heavy-duty truck, so 35-40. don't forget to check your spare tire for serviceability and pressure; have a safe road trip!

caged

first of all, is your jeep stock with stock size tires?

for instance, a 31 inch tire doesn't come stock on a cherokee, so inflating that to 35-40psi is just too much pressure. that tire would be used for a full size pickup that weighs twice as much. so to run smooth on a cherokee would only require about 25-30psi.

but for a better idea, you can take a piece of chalk and rub it across your tire, then drive around the block and see what area of the chalk was rubbed off. if in the center, you have too much air, on the sides, too little air.
you want it to scuff off evenly.

for instance, my 36's runs nice at 9-12psi on my cherokee.

stock tires, i'd say no more than 32psi cold.

j33pc1233p

Wow! when I first read this I was thinking the same as Eva. Actually my thoughts were "huh?!?! ever looked at a tire??" I've always gone by what the max PSI indicates on the side of the tire. But you guys make an excellent point! Not all vehicles weigh the same...boy do I feel dumb. Seems so obvious now, but I'm sure lots of people haven't taken this into consideration. Good post. Drive safe 40Below

BTW..Where ya goin?

darknight

according to the manual, with stock tyre size 32 psi all round

Eva

Okay, okay- I should have specified to check it when it's warm, and after the vehicle is loaded for the trip. And the other good points raised. I am, however, accustomed to professional drivers, and to adjusting tire pressure according to load. I owned a commercial fleet facility for 10 years, have been working on trucks and 4x4's for over 20 years, and some processes are so natural to me now that I forget they took someone to teach me so many years ago.

tiwvr1- As caged also mentioned, non-stock tires make a difference. Your answer was as simplistic as my initial one, and you should tone the attitude down. Your vehicle doesn't know what tires it has on it either.

Sorry to the OP for giving a simplistic answer to a not so simplistic question, and please take all of the recommendations into consideration. Have a safe trip!

40below

Thanks everyone for your posts. Great info and good stuff to know!!!!

fantic238

40psi is too much. 32psi is ok.

tiwvr1

sry eva, I am just sick of people that don't know anything comin into work and insisting that the pressure on the tire is right, not the pressure by the manufacture, and those of us who have been doing it for 10 years are wrong.

I was assuming they have stock tires and load range. We actually have a book at work to convert diffrent load ranges tires on diffrent vehicals, so we know what the air pressure is suppose to be.

Once again, sorry eva, wasent really geared towards you.

Eva

I hear you about laypeople insisting they know more. No harm done, and thanks for apology.

It can be difficult to translate years in industry or working on Jeeps into a forum answer. In my shop, we actually determined what the proper pressures should be if anything had been changed, and made a sticker for the drivers where they kept the air pressure gauge. That book of yours would have been handy. ;-)