Safe tire pressure to run on road?

Wethy

Wethy

Member
So ive been chalk testing my tires. This was my latest chalking after letting the tires cool for a while then dropping to 26psi ans going for a test drive. What is too low to run on the road with these 35/12.50/17 ridge grapplers?

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I found that the Rubicon stock setting of 37 cold psi kept making my light activate after long drives, and my pressure would be in the lower 40's. So, I now run 37 hot psi, and no light issues, feels better on the road, etc. I have not done the chalk test though. This is for 255/75r17 though, but my point is, the tires on these things heat up like mad because they are aggressive. So how can the stock for all wranglers be 37 cold? They certainly heat differently then a gsa, at least thats my guess given the lack of rolling resistance.
Hmm....rambled a bit....guess I'm trying to say YMMV, but that looks pretty even to me.

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Wethy said:
So ive been chalk testing my tires. This was my latest chalking after letting the tires cool for a while then dropping to 26psi ans going for a test drive. What is too low to run on the road with these 35/12.50/17 ridge grapplers?

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I'm always at 28-30 psi with no issues. It looks like your running factory wheels 7.5" wide I think on a 12.5 tire and it might be pinching those tires a bit to where your not going to get a perfect chalk test. I probably wouldn't go to much below 26, but that also depend on the weight of rig and how things feel.


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Journeyman said:
I'm always at 28-30 psi with no issues. It looks like your running factory wheels 7.5" wide I think on a 12.5 tire and it might be pinching those tires a bit to where your not going to get a perfect chalk test. I probably wouldn't go to much below 26, but that also depend on the weight of rig and how things feel.


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True enoygh are you in factory rims as well or aftermarket?

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JKDream said:
I'm on 37x12.5x17 Ridge Grapplers - and I found they wear the best between 24-26psi.
Any higher and they ride the middle tread quite bad.
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Ill bear that in mind. Although im at 26 now and theres still lots of chalk left lol
 
You can drive on pretty much any pressure on the road safely. It comes down to how you drive as to if it's safe or not.

As for your pressure, your going to have a hard time getting it perfectly even due to how narrow the factory wheels are.
 
Good thread!! I just got bfg tko2s put onto my jeep they are kind of an odd size but measure out to right about 36 inches. I have aftermarket 20 inch wheels (which I want to swap out and go back to a smaller size ) and the tire shop had my tires at 55lbs. It rides terrible. I just dropped them to 35 and I want to start checking them from there. They are an E rated tire. Any other suggestions for setting air pressure with this kind of setup? I like the chalk technique.


2012 Sahara
 
Great Pumkin said:
Good thread!! I just got bfg tko2s put onto my jeep they are kind of an odd size but measure out to right about 36 inches. I have aftermarket 20 inch wheels (which I want to swap out and go back to a smaller size ) and the tire shop had my tires at 55lbs. It rides terrible. I just dropped them to 35 and I want to start checking them from there. They are an E rated tire. Any other suggestions for setting air pressure with this kind of setup? I like the chalk technique.


2012 Sahara
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With a tire that large I'd start no higher than 32psi. Chalk testing will get you the best results. Running to high a pressure will not only cause poor wearing but also can cause odd handling characteristics and a rough ride. I'm running 35x12.5 BFG KM2's on a 9" wheel and found 27 is best. Been running that for 5 years and doing a 5 tire rotation. I have 30k miles on them and they are only now showing some slight signs of cupping. Still have 30-40% left too.

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jesse3638 said:
With a tire that large I'd start no higher than 32psi. Chalk testing will get you the best results. Running to high a pressure will not only cause poor wearing but also can cause odd handling characteristics and a rough ride. I'm running 35x12.5 BFG KM2's on a 9" wheel and found 27 is best. Been running that for 5 years and doing a 5 tire rotation. I have 30k miles on them and they are only now showing some slight signs of cupping. Still have 30-40% left too.

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Awesome thanks. Also how do they do on the highway? I drive roughly 70 miles to get to the trail


2012 Sahara
 
I run 33" Goodyear Silent Armor (E rated) A/T tires at 35psi on highway and they seem fine plus I've noticed a big increase in MPG.

However, after a trail run I don't normally air up until I hit a gas station 15-30 miles down the road as the kids and wife need a bathroom brake. Is running between 18-25psi on the highway at 50 to 55 dangerous until I hit a station? Some roads can be fairly winding and of course I'll go slower.
 
I run around 32 psi on the road. If you have a super chips programmer you can reprogram your TPMS to not flash the warning on the dash till you get below 30, or whatever number you choose.


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Lots of good info thanks again. One more question. As of right now I don't have beadlocks. I am planing on getting them sometime but in the meantime how low can you safely air down for trails.


2012 Sahara
 
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