O.K On my 05Rubicon it says to have the tire pressure at 33 psi, is this when it's cold (before driving) or hot (after a few miles)? Thinking of doing the chalk test for kicks. How should I go about it? Heat the tire up first????? Argggg!!! Confusing Need Clarity
Recommended tire pressures are always given cold. Summer and winter can make about a 5 psi or greater difference so they need to be checked as the weather changes.
To do the 'chalk' test, you want them cold. You run some chalk lines across the tread and drive a short ways straight. Then look to see how much chalk is left.
For the best traction, having only about 1/4" to 1/2" max left on the edges gives the best grip, but having the best grip will cut down gas mileage by a half a mpg or maybe 1 mpg.... I will take the best grip thanks.
When I ran 31x10.5's, 26 psi gave me the best footprint in my at the time stock CJ7 and the tires wore down perfectly even. For my 33x9.5's
26 psi gives the best print, but the sidewalls are so tall it feels mushy on corners. I compromised and run at about 30 psi for the better 'feel'.I also found out that running in iffy weather (snow squalls) with my front hubs locked so I can 'shift on the fly' into 4x4 costs me 2-3 liters of gas for a 200 km run. For the extra safety in bad weather, I don't mind the extra gas. You don't have that option, your front is always turning.
Hey there is another reason why CJ's get better mileage than the TJ's.... ;-)
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT'sFrankW wrote:
In the real world, it doesn't matter very much. I check cold tires whenever possible, but if I am out and notice a tire is low, I still put the same amount of air in.
In the grand scheme of things, a pound here or there doesn't make much difference.
If I've been running across Nevada or similar, I just check the remaining tires and inflate the oddball up to about half a pound less than the rest. Around town or short freeway runs, I've never noticed much difference between cold and runtime.
J Strickland proclaimed:
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