Street Tire Pressure for BFG A/T 33x10.5s?
- Thread starter w_b
- Start date
highlandercj-7
Explorer
Normally your not going to run any more than 28 PSI. I run my 35x12.50's on my CJ-7, at 22psi on the rear and 24psi on the front to give the best contact pattern. 50 psi would blow the centers out of them and make your XJ ride like a brick. The larger the tire the less the psi. A lighter vehicle cannot work the tire when it's over inflated. My full size truck only required 26 and 28 psi to keep the 35's in the best contact pattern. My friend ran 52" Michelins on rockwells at 0 psi on his CJ because there wasn't enough weight to work the side walls 
w_b
Observer
We ran to the store earlier today with the tires at 30 - front, 28 - rear, and noticed the outside lugs of the rears still had the dust on them from our dirt road which we left behind 45 miles ago. I'd say just a little over an inch on the outside of the tread wasn't on the pavement.
The fronts didn't show this, but they scrub when turned, so...
Oh, and (rant on) why is it I cannot find a tread depth gauge anywhere?! Autozone - the guy didn't even know what I was talking about, and I had to explain what it was; Big-O, nope; China's Redistribution Center (aka Wal-Mart), not even there. Sheez...(rant off)
The fronts didn't show this, but they scrub when turned, so...
Oh, and (rant on) why is it I cannot find a tread depth gauge anywhere?! Autozone - the guy didn't even know what I was talking about, and I had to explain what it was; Big-O, nope; China's Redistribution Center (aka Wal-Mart), not even there. Sheez...(rant off)
XJLI
Adventurer
lololol seriously? the contact patch at 50, hell, 40 PSI is dangerously small on a Jeep. I run my 33x10.5 BFG MTs at 33 on the highway to squeeze 1-2 more MPG out of the Jeep, and leave them around 27/28 normally.
mountainpete
Spamicus Eliminatus
That feels rather high to me. I would be more comfortable between 33 - 37 depending on the amount of load. In fact I don't believe I have ever had a AT or Mud tire running over 40 PSI at any time.
w_b
Observer
laughing...
Here you go :wings:
Hey, uh... how much for that one?
It's only one short trip and I haven't put the 4.10s in yet, but we got 19.7 MPG @ 70 MPH (taking into account the odometer running 16% slow). That makes me feel a bit better after getting just under 8 MPG putting around in the desert.:Wow1:
That'd be 18 psi in the front, 16 psi in the rear or less. I haven't done the chalk but it is at that pressure the edge of the tread first makes contact with the ground. I'm not sure I'm comfortable running a tire pressure that low over the road. Maybe if I had an I.R. heat gauge and could check the temps of the tires, but still it violates my reality somewhat.
Recommended tire pressure for the stock tires, 195/75s, is 33 front and rear. It's not just psi, it's volume too, right?
This does remind me of a funny story though. My kid had a Samurai with a worn out motor as a daily driver with 31s. In an effort to squeeze all the gas mileage out of it he could and to reduce rolling resistance so he could run it on the freeway, he'd run those tires at 50 psi. It was like riding on basket balls. I think his contact patch was about 2" wide. You could easily see daylight under the outside tread of the tires. The things kids do...
ntsqd
Heretic Car Camper
On my ~3500 lbs. Xcab yota with 33-10.50 BFG A/T's I run 30-32 on the highway and aired down is 19 psi.
http://www.plews-edelmann.com/brochure.cfm?brochure=3040&location_id=3800
Item #925D
Start with the mfg and ask them where you can buy one.
http://www.plews-edelmann.com/brochure.cfm?brochure=3040&location_id=3800
Item #925D
Start with the mfg and ask them where you can buy one.
Maximus Ram
Expedition Leader
here ya go.. Pick one:sombrero:
http://shop.ebay.com/items/_W0QQ_nkwZTreadQ20DepthQ20GaugeQQ_armrsZ1QQ_fromZR40QQ_mdoZ
ox4mag
Explorer
I know it sounds high. Sounded high to me too when I looked into it but if you look at your sidewalls, the PSI should be there and it specifically says for max loads it should be at 65 depending on the exact tire you have. So for loads in mid-range, it should probably be somewhere around 45-50 on the freeway with obvious reductions when off-highway.
I adjusted my tires to compensate for this as I had previously been running them at 30PSI. The change was significant with approximately a 10% increase in gas mileage.