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  #16  
Old January 22nd, 2021, 10:06
RCP Phx RCP Phx is offline
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Re: XJ 16" Wheel / 31" Tires - Best Balance of On/Off Road Perfromance?

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Originally Posted by MiWiAu View Post
Nice! This forum needs a "like" button. I measured my back spacing at 5.25", but I'm okay adding spacers as required.
Thanks for the calcs! Are they specifically load based pressures, or does it also consider bead retention?
No, it doesn't take any conditions at all (kind of a joke). For 50yrs I just used my head based on my vehicle and whether it was snow, mud, sand, or rocks. The other thing is wheel/tire size.
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  #17  
Old January 22nd, 2021, 11:47
Black1990jeep Black1990jeep is offline
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Re: XJ 16" Wheel / 31" Tires - Best Balance of On/Off Road Perfromance?

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Originally Posted by MiWiAu View Post
Nice! This forum needs a "like" button. I measured my back spacing at 5.25", but I'm okay adding spacers as required.



Thanks for the calcs! Are they specifically load based pressures, or does it also consider bead retention?
The values given are based on standard rims, not bead lock rims, these are recommendations on what seems to work well, sure you can blow a tire off a rim even at higher pressures given the wrong circumstances, but these values are a good rule of thumb. You dont need to go that low, these are just the lower reasonably safe limit based on trial and error. I typically have been running 12 psi on my 33 x 12.5 tires in my XJ although that calculators says I can go to as low as 9 or 10 psi. I drive slow, and am very careful on the rocks. You can even go lower still as the back,of the calculator states you can cut these minimum pressures in half (ie 5 psi!) in soft snow! But in that case I would be going very very slow with easy steering, on a smooth snow pack, no big rocks. Id likely put the snow chains on in that case!

When I first started wheeling I was only going down to 16 psi cause I was frightfully concerned about blowing the tire off the rim, but after a few Death Valley rock crawls, and talking to other jeepers on the trail, I learnt that my pressure was too high, so now I do 12 psi as my standard trail pressure, knowing that I can go lower if needed. the improvement between 16 and 12 psi was significant. I may even try a lower pressure in the near future if the trail requires it to see if things can get better still

worse case I pop a tire off the rim, but I got a spare for that. But under most circumstances I should be ok even with 9 or 10 psi. sure wedge the tire on a rock, and turn the steering and the tire may come off, even at a higher pressure.

It is a learning curve.
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  #18  
Old January 22nd, 2021, 11:55
Black1990jeep Black1990jeep is offline
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Re: XJ 16" Wheel / 31" Tires - Best Balance of On/Off Road Perfromance?

ps you will want a good deflator kit to save a lot of hassle

https://parksoffroad.com/prodreview/...asis/oasis.htm

I got these, which is where I got the pressure calculator. the deflators are set to the pressure you want with a screw, and will deflate automatically to that setting, just screw it to the valve stems, when it stops hissing it is done ( I then confirm pressure with a gage) the set comes with four deflaters so all four tires can be deflated at once

a friend has the arb deflator, but it is more of a pain, as you need to unscrew the valve stem valve and manually operate the deflator, one tire at a time. Mine automatically deflate so I can spend time unhooking my sway bar and be ready for the trail before he can get his tires deflated.
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  #19  
Old January 22nd, 2021, 11:56
denverd1 denverd1 is offline
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Re: XJ 16" Wheel / 31" Tires - Best Balance of On/Off Road Perfromance?

XJ's are pretty light. IMO D is too stiff a sidewall. C's are perfect.

go 265
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  #20  
Old January 22nd, 2021, 12:31
MiWiAu MiWiAu is offline
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Re: XJ 16" Wheel / 31" Tires - Best Balance of On/Off Road Perfromance?

265 is my preference, but I was hoping to stay with a 70 profile (~31") for my 16" rims. However, I don't see any C load range in the 265/70-16. There are a few C options if I step up to 265/75 (~32"), but that will require more trimming and a gearing tradeoff (stock 3.55 gears with auto, currently).

Decisions, decisions!
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  #21  
Old January 22nd, 2021, 13:40
maxbraketorque maxbraketorque is offline
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Re: XJ 16" Wheel / 31" Tires - Best Balance of On/Off Road Perfromance?

Quote:
Originally Posted by Black1990jeep View Post
ps you will want a good deflator kit to save a lot of hassle

https://parksoffroad.com/prodreview/...asis/oasis.htm

I got these, which is where I got the pressure calculator. the deflators are set to the pressure you want with a screw, and will deflate automatically to that setting, just screw it to the valve stems, when it stops hissing it is done ( I then confirm pressure with a gage) the set comes with four deflaters so all four tires can be deflated at once

...
These are cool. I just ordered a set.
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