Outer Limits 4x4 Board

Hey i have 31" x 10.5" tyers, what tyre pressure should i put in(psi).
I read the side wall and that said 50 or some crazy figure i thought was too much, i asked my brother who is into 4x4's and he didnt know so i brought it to you guys,

p.s. i only just my p's, don't laugh at my stupidness...

DEpends on the car too,

Hilux I am guessing,

Try about 30-32 in the front and 28 in the back.

All depends how you want the car to run on the road, what you carry, do you have a V8 in it etc

Stock petrol sigle cab lux those numbers lowest, any other things keep adding 2.

V8 + 2
Dual Cab +2
Tray full of tools +2
etc

Drive in and ask your tyre shop

Around 30 on road and 15 off is a good start.
It all depends on a lot of factors though. The weight of your 4wd the type and size of your tyres and the width of your rims.
Paul.

thanks, just letting you guess know its a 1980's 45 series troppy.
i got like 40 psi in at the moment, drives nicely, i also got 15" rims don't know there width, if bad_r reads this he will inlighten us because it was his car originally(he is the one who didn't know tyer pressure).
diesle as well.
cheers.

sorry that was guys not guess...

Depending on load and accessories -30-40 psi on road.

pump them up to 50 and wait for them to go back down... and then pump them back up.

it's a 45 troopy, not much luggage, 30 is a little too soft for it i think, i ran it for a couple of years on 30, and it wore the outside edges too much,

from memory dean, it ran well with 36 psi, maybe more in the back, but you know how much stuff i used to cart around.

im a mechanic, run 50 in them, i got same tyres , let them down if goin bush

yeah i have 50 in em now, feels like power steering, very light, i like it, drifting made easy

huntagrunta wrote:...run 50 in them...

50 is great if you want them to wear in a narrow band down the middle of the tread, ride like you've got no suspension, and skid all over the place in the wet, but it will provide good fuel economy.

a reliable method of setting your tyre pressure is the '4psi rule':

set your tyres to what you think is a decent pressure, then go for a drive at or above 100km/h for 40 mins to an hour, then check the pressure again. If the pressure you set cold was about right, the hot pressure will be able 4psi higher. if your set pressure was too low, the pressure will rise more than 4psi due to excess heat. if too high, the pressure will not rise as much. This method will give a good compromise between wear, ride and handling. of course if you want to you can bias your pressures to improve handling, economy, wear or ride, depending on what's important to you.

don't try it on a rainy day, the water tends to cool the tyres as you drive and you won't get a reliable reading. also note that pressure changes with changes in ambient temperatures so it's important to check tyre pressures regularly.

cheers

Brian

huntagrunta wrote:im a mechanic, run 50 in them, i got same tyres , let them down if goin bush

and this makes you the guru on tyre pressures?? Mate, been swinging spanners for over 17 years but that doesnt make me a tyre pressure guru. I used to own a FJ45 troopy, and depending on load/accessories as well as terrain/driving style, 30-40psi was good for me. This is what worked for ME.

I would say that 50psi is a massive over kill. As dumbdance said it'll wear a strip of tread down the centre of your tire much faster thatn the rest and handling/comfort on bumpy roads would be at a minimum.

Id say 32-38psi on road and 10-15psi off road

38psi

like it's been said. depends what you want.

I reckon

low 30's for comfortable ride at the loss of fuel economy and tyre wear

high 30's better economy reduced tyre wear but a little bumpy.

I run mine at 38
Steve

will buggered wheel/ kingpin bearings affect the temp change method?

bad_religion_au wrote:will buggered wheel/ kingpin bearings affect the temp change method?

to some extent yes - stuffed wheel bearing runs hot anyway, and causes excessive toe out and negative camber, which causes front tyres to scrub/scuff -> heat, similar effect from stuffed king pin bearings.

fix them up - it's easy and relatively cheap, around $45/side for wheel bearings and $200ish for knuckle rebuild kit, a pot of grease and an afternoon in the sun and you're all set.

dumbdunce wrote:

bad_religion_au wrote:will buggered wheel/ kingpin bearings affect the temp change method?

to some extent yes - stuffed wheel bearing runs hot anyway, and causes excessive toe out and negative camber, which causes front tyres to scrub/scuff -> heat, similar effect from stuffed king pin bearings.

fix them up - it's easy and relatively cheap, around $45/side for wheel bearings and $200ish for knuckle rebuild kit, a pot of grease and an afternoon in the sun and you're all set.

that's the plan, just gotta convince 45punkbus that it's a good idea...

either that or swap in the spare front axle sitting out the back, with no wheelbearing or kingpin bearing play at all... his call

i got a plan i provide the $$$ u provide that lovely afternoon in the sun, don't forget that tub of grease

that sounds gay even if you are my bro

Use dumbdunce's 4psi rule. I've been using that one for 20 years and is pretty spot on. (got 70K out of BFG MT and them sold em for $100 each ! )

Bet you can't get them to hold 70 psi

in 4x4 monthly didn't roothy fill his spare to 100psi to act as a compressor cylinder

I run 34-36 depending on gauges what they say