[want33s]

There's a bit of talk about tyre pressures in another thread so I thought I'd start this one so noobs can find the relevant info easily in a search.
State your tyre size and road/offroad pressures.

Mine: Sierra LWB
33x10.5-15 Silverstone MT-117 extreme on 15x7" rims
20psi all round ON road
4psi front.. 3psi rear OFF road. (Staun beadlocks)


EDIT: added rim size.

[Scrawny]

31's on 15x8 rims

- 18psi on road
- 8ish off road (if I went off road )

[scottysj80]

mine: swb sierra
235x75 road tyers on 15x7 rims
20-22 psi on road
and down to 10psi off road

[JrZook]

235/75 BFG MT on 15x7's
10psi offroad
40 psi on road

[Scrawny]

JrZook wrote:

40 psi on road

How does it ride???

[shep]

31s on 15x8 20psi on road and 9 to start with off road.
my last tyres (32s) worked well at 4psi.

[Cade]

i have 235/75/15 with 36 psi

[shep]

Cade wrote:

i have 235/75/15 with 36 psi

the recommended pressure for the standard tyres is 22psi
bigger tyres need less air.

[JrZook]

ScrawnC wrote:

JrZook wrote:

40 psi on road

How does it ride???

Quite well for a sierra actually. OME light duty springs and oil filled adjustable shocks. So much nicer to steer and after 80000ks the tyres are wearing dead flat across the tread.

Dan

[Cade]

pretty sure my tires wall says 36psi max

Khumo A/T 235/75/15

[royce]

235/75R15 Wrangler ATR

22psi, 50000km and worn ok except for the inside edge from too much camber and the wobbles from dead struts , could of done another 30k I reckon

[Cade]

hmmmm maybe i need to drop some psi

do you guys go by whats on the tire wall

[shep]

Cade wrote:

hmmmm maybe i need to drop some psi

do you guys go by whats on the tire wall

no

[Cade]

interesting i want go experiment now

but some advice guys

i leave on Monday for my road trip from Perth to Exmouth (3000km round trip)

what psi should i go

not sure if i want to experiment going on a big drive

[Scrawny]

Lots of highway miles requires a little more pressure. I would up the pressure to about 25psi for the big trip. Sierras are too light to have anything more than that in the tyres, I think the tyre placard on the car says 22psi?? 40psi is for Patrols and Landcruisers, not Sierras.

[Cade]

i was just going by whats on the tyre wall the inflation reccomendation

[ZukChiK]

Cade, if you have a full load on your long journey I would suggest around 30-32 PSI for highway speeds

[felix]

22 on road
start at 10 offroad.. unless im just having a play in some dirt then i cbf.

31x10.5 bfg muddies, on SWB vitara.

[Cade]

just checked my tyres

they are actually 225/70/15 max pressure 35psi

i just thought that was how much you are menat to inflate too

DOWN she goes

run on 32 for the trip to exmouth

[ajsr]

34" swampers ltb's 6-8 lbs off road 15 lbs on road(rairly on road)

[joeblow]

JrZook wrote:

ScrawnC wrote:

JrZook wrote:

40 psi on road

How does it ride???

Quite well for a sierra actually. OME light duty springs and oil filled adjustable shocks. So much nicer to steer and after 80000ks the tyres are wearing dead flat across the tread.

Dan

people...its not the ride that is important...that is a secondary issue...the most important thing with pressures is braking performance, the higher the pressure, the poorer the braking performance!

as for me with 33's....
max 18 on road....
10 offroad.....(i'm 1.5 ton laoded!...)

[twitchy]

Jesus h christ Joe, where the flying frog fuck did ya dig that bit of gold from????? The Higher the pressure the worse the braking?
Low air pressure will INCREASE bad handling & braking. Out of all the above mentioned pressures If I was on the the tar I'd rather be with Cade or Jnr if something hairy happened.

[alex]

235/75R15 Wrangler MT/R on my swb sierra i run 25 on 15 off

[royce]

higher pressure reduces the amount of rubber on the road, thats why you let your tyres down off road, more traction

less rubber on the road, less grip for braking, less grip for conering.
the only benefit for high pressures is increased sidewall stiffness which helps turn in, but thats easilly fixed with decent suspension settings

too low pressure also cause the sidewalls to flex too much and overheat, a good rule of thumb for fully loaded pressures is you want about a 2psi pressure increase once the tyres are hot, any more and the pressure is too low, or your too overloaded for the tyre (unlikely on a sierra or vitara)

the key here is not higher or lower, its correct, car companies pay engineers big $$$ to sort this crap out, some dude down the tyre shop isnt more correct, plus the load rating on most 4wd tyres could easilly support the entire load with 1 tyre.

[felix]

Exactly, if you realise what the LT (light truck) tyres we run are designed for, you'll know why our little zooks only need lower pressures.

[Taff]

i have only ever run 20 max on the road.

dont see any point going higher. if your worried about handling in a zook with muddies you must be on drugs anyway.

[mike_nofx]

Cade wrote:

just checked my tyres

they are actually 225/70/15 max pressure 35psi

i just thought that was how much you are menat to inflate too

DOWN she goes

run on 32 for the trip to exmouth

Open your door and look at the white sticker on the side of the dash.
The tyre wall says MAX! They are designed to fit a range of cars not just zooks.

I run 20 psi front and 30 psi rear ON road. 30 psi for rear is because of welded diff, makes it a bit easier on tight turns.

8-10 psi off road.

[BlueSuzy]

I run 26-28psi with my 33's..

Under 26psi i can feel the car slowing quicker as the tyres grab the road more.
Over 28psi i can feel the car jolting and bumping all over the place like its on ice.

I run 12psi offroad, Scared of popping a bead...

[joeblow]

twitchy wrote:

Jesus h christ Joe, where the flying frog fuck did ya dig that bit of gold from????? The Higher the pressure the worse the braking?
Low air pressure will INCREASE bad handling & braking. Out of all the above mentioned pressures If I was on the the tar I'd rather be with Cade or Jnr if something hairy happened.

we have done the tests............i'm not talking purely off road settings, i'm talking about new tyres, new compund and sidewall, size, volume and vehicle weight. a car has an 'ideal' setting that will see it perform well in all conditions, go above this and braking suffers, go too far below and cornering with speed suffers, etc, etc.measure out a strech of road, than hit the brakes at 40 psi and see how far before you stop, then do the same at 20 psi, you will notice the vehicle stops a bucket load shorter before locking brakes. simple maths....try it yourself....i had to.

[oscar]

31/15/8 simex et's
22 on road
6 offroad, a hour or 2 later 1 or 2 tyres has 0 in em.