Philbert

iTrader: (2)

Hi everyone,

I'm slowly learning more and more about how to take care of cars - I'm so far ahead of where I was ten years ago, let alone 5 years ago...and I have a long way to go!

One place I'm especially not yet learned in is tires.

in 2004 I had Big O Tires install a 4" Pro Comp lift kit to my 87 4runner, along with 15 inch black rims, and BFG 32" x 11.5" tires. The sales guy told me to inflate the tires to 35 PSI. He also forgot to adjust the torsion bars after the install, so the front suspension was riding on the frame for a couple months....(and I had no idea to look out for it at the time.).

Anyway, fast forward several years. I looked at my driver door well and the OEM specifications on the tires is 26 PSI FRONT, and 25 PSI REAR.

My question is, with aftermarket tires, do I still follow the OEM recommendations, and stagger the PSI for the front and rear tires? This was for highway and around town driving - not offroading.

Thanks!

waskillywabbit

iTrader: (-1)

Read the tires, not the door jamb.

:wabbit2:

Philbert

iTrader: (2)

Thanks Rabbit - that was fast

Tire reads "Max load of 2500 lbs at 50 PSI". I'm assuming that load rating is PER tire.

either way, this shows the MAX rating...is there a way to determine the "normal" PSI to use? Any reason to have the same pressure among all four tires, versus "staggered" like the door stop says?

Told you it was a dumb question....

xxxtreme22r

search up tire chalk test. Ive never done it, but I've heard it works pretty well. Every rig even with the same tire/wheel is gonna be different because of the amount of weight the owner carries on a daily basis.

snobdds

Do a chalk test on the tire. Basically you want the tire with just enough air so the tire rides flat on any given surface.

Take some chalk and make a straight line across the tire. Drive on it for about 100 yards and note where the chalk rubbed off. If it's in the middle, then there is too much air in the tire. If the sides are rubbed off, then there is too little air in the tire. Adjust the tire pressure and repeat until the chalk is rubbed off uniformly on the tire. Then your set.

xxxtreme22r

forgot to mention this only works well if your tires are properly aligned, especially caster/camber.

4Crawler

iTrader: (3)

Some tips below:
- http://www.4crawler.com/Diesel/Tires...roperInflation

Philbert

iTrader: (2)

Thanks everyone!

Did some reading on the chalk test this morning, and lots of 4Crawler's site (I'm always amazed at the stuff on there I haven't seen YET!).

Looks like the chalk test is my next step - along with the "Business card test" I aired up to 35 PSI before my trip to Yosemite this past weekend and got about 20 MPG, which is great for me on stock gears and 32" tires. I'll spend more time researching this, and trying out different pressures when I get back from my work trip this week.

Thanks again all!

jadatis

Tire pressure is all about weight on the tire and speed you maximaly drive with.
I once got hold of the formula, the European tyre-makers use to determine the advice pressures for radial tires.
Learned myself Excell to make spreadsheets for it.
Translated a few to English to go worldwide with it.
Discovered that in America they used the same formula but with another power in it, wich lead to lower pressures , so sooner tire-damage. In 2005 ( after the Ford/Firestone-affaire coincidentially??) America swiched over to the European power , saying it was for having globally the same system.
http://cid-a526e0eee092e6dc.office.l...0tyre-pressure
In this map on my skydrive of Hotmail, spreadsheets and examples . Download the spreadsheets and open them in Excell or compatible programm to use it, the browser will try to open it but cant handle some things I used in it. If you get this message click on the name of the spreadsheet above , and click in the new screen on Download.
If downloaded you can check it first for virussus if you want.Then open them in the programm you have on your computer.
If you cant work it out give me the details. From this link you can navigate my complete public map for more.

Your tires are probably C-load tires, because the 50psi is stated like you mention.
If there is "max load xxxxlbs at yyy psi" on the tire, this is the reference-pressure as it is called in the formula. I dont know how it is in America, but in Europe the normal car tire/P-tires/standard load, had a maximum pressure printed on it like "maxpress yyy psi", wich is not the reference-pressure, wich is 2,5 bar/36 psi to calculate with. Also for Extra load/XL/reinforced max pressure only printed, but reference-pressure 2,9 bar/42 psi , I think they call it B-load tires and Ptires A-load. So you have to look how the pressure is printed on the sidewall.
Greatings from Holland.

Philbert

iTrader: (2)

Wow, Peter, thank you for the details! I opened up one of the excel documents at the link above and started working on it but it's metric I'm traveling for work this week but will try to get to it when I return. I really appreciate your detailed response and the excel document - thanks again!

Phil

IanB

Metric IS what the rest of the world uses, lol.

If you visit Tirerack.com or the manufacturer's site you should be able to find the specs you need in metric as well as standard.

Philbert

iTrader: (2)

I know - I prefer Metric (Own a Datsun, Toyota and BMW ).

Haven't had a chance to try chalk test - been raining since I got back. Then I'm on the road again for work this week...arg. Also need to diagnose my Datsun....had been pulling to the right under braking recently, and on the freeway on the way home from the airport Friday, I braked for an offramp heard/felt a "clank" from the front right. Took surface roads home with caution. Makes an audible clicking/sticking noise when braking. I think I may have lost a caliper bolt....just haven't had time to check it out since my parents have been visiting!