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Determining correct tire pressure for larger tires...help...

j.o.y.ride

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I usually start cold around 27 and when they warm up to 28-30 it's ideal. Beyond that the outside treadblocks start to lift and it's like driving on ice skates.
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On Friday, I upgraded the tires on my 2022 JT Overland from the stock 255/70R18 Bridgestone Dueler H/T 685 to 275/65R18 Falken Wildpeak AT/3. I got the SL load category (same as what was on there).
Overland stock tires are best at 38. I confirmed that with my own when it was on stock tires.
I ran Falken A/T Rubicon take-off wheels and tires for a while and was best at 36 psi, again, double-checked.
As a general rule, the larger the foot print of the tire under the same truck weight, the lower the PSI you would run. It's the PSI, pressure per square inch that supports or holds the truck up.
If the foot print is larger, you have more square inches on the ground so it takes less pressure.
36 pounds per square inch......... acting on the square inches of the foot print.
If you increase the width of the tire, there's more square inches on the road so it takes less pressure working on those square inches to hold the truck up.
35 square inches of tire on the road, 36 psi - if you went to a smaller tire that had only 33s square inches of rubber on the road you'd need to run about 38 psi.
A larger, wider tire might have 38 square inches on the road so you'd run about 33 psi
So you have to go by what's best for the tire you have, and the weight of your truck.

Me - I contacted General Tire, spoke with a "consumer engineer" and gave him the weight of my truck, the size of their tires I had bought and he gave me the recommended PSI for my truck based on the weight, the tires I had taken off and other factors.
 

CJXJJT

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When I purchased my Rubicon, I watched my falken 33's very closely for the first couple of thousand miles. The best indicator for me was the wear on little tits from the mold. I noticed the front wears faster in the center of the tire at the same pressure. I settled on 28lbs cold at about 60 degrees outside. At 70-80 degrees my tires will read 29-30 cold then warm up to the low 30's. When it's cold in the morning my pressure drops to approximately 25-26 at start only to come up to 29-31 within about ten to fifteen miles or so.
I also purchased a tread depth gage on line for a few bucks. I keep a pretty close eye my tires for even wear. This pic was taken at 78 degrees. Good luck!
Jeep Gladiator Determining correct tire pressure for larger tires...help... 16526691727324006457066500065771
 

ospreyfe55

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I did the chalk test on my new 35s. When the tires are cold pressure is 25-26psi, once warmed up they read 30 psi.
 
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0REDSOX7

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Did you adjust the tpms alarm with the tazer??

When I purchased my Rubicon, I watched my falken 33's very closely for the first couple of thousand miles. The best indicator for me was the wear on little tits from the mold. I noticed the front wears faster in the center of the tire at the same pressure. I settled on 28lbs cold at about 60 degrees outside. At 70-80 degrees my tires will read 29-30 cold then warm up to the low 30's. When it's cold in the morning my pressure drops to approximately 25-26 at start only to come up to 29-31 within about ten to fifteen miles or so.
I also purchased a tread depth gage on line for a few bucks. I keep a pretty close eye my tires for even wear. This pic was taken at 78 degrees. Good luck!
Jeep Gladiator Determining correct tire pressure for larger tires...help... 16526691727324006457066500065771
 

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CJXJJT

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Did you adjust the tpms alarm with the tazer??
I did at first with the Jscan. But I turned it back because its a quick look at tire pressure every time I fire up the engine. Just a good fyi for me whenever I get started.
 
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0REDSOX7

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t I turned it back because its a quick look at tire pressure every time I fire up the engine. Just a good fyi for me wh
Got ya! I still think I need to drop my rear tire pressure more, based on the tire wear that I see right now, but, will keep tinkering with it.
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