newbie question about tire pressure

[lordhowe]

I have a set of 33x12.50 bfg mud terrains riding on 15 x 8" rims. i was wondering what pressure i should be running them while on road. and what's a good rule of thumb for off road pressure.

right now i have been running them at 40 PSI on road and half that in sand. I don't want to wait till noticeable tire ware before i changing the pressure.

thanks!

 

[fourwd1]

40 PSI is waay too high.
Look for a sticker on the door jamb that gives you the tire pressure, or in the owners manual.
And in the sand I'd go down around 12 PSI or so.

Of course I wouldn't take my truck in the sand at all.

 

[lordhowe]

i know the stock recommended tire pressured based on stock tires, but i'm running 33x1250's and wasn't sure what the correct on-road pressure for that tire size....

 

[Steve8v92]

The correct psi anywhere from 29-32 I run mine at 31 lbs.
Same tire.
Would never run a tire at 40 lbs, hahaha

 

[lordhowe]

The correct psi anywhere from 29-32 I run mine at 31 lbs.
Same tire.
Would never run a tire at 40 lbs, hahaha

31 PSI? wow that's pretty low from all of the research i have found.... how is your tire wear?

 

[RedApe]

I would agree with above stated.
Street I ran 28 on the street with my (33x12.5) Swampers on my 82 truck... and running 30 on my 4Runner.

Trail On the trail, I was running 10 in front, and 8 in rear on the pick up.
4Runner, 12 fr/rr.

Chalk Test..I'd recommend doing something similar for your application. Each vehicle's mass, and the loading characteristics of the name brand/model of tire will vary to some degree.
Draw a line of chalk across the tread. Drive around the block to see how much contact patch is actually in use at a given pressure. 85%+ of the chalk should wear off while driving if your using correct pressure.

Hope this helps...

 

[fourwd1]

I run my 36's at 28-30 on the street and 10 in the rocks, FWIW.

 

[lordhowe]

i will do the test, thanks alot guys