Geolandar 35's chalk test: what are you running your pressure at?

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jsims006
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Geolandar 35's chalk test: what are you running your pressure at?

Post by jsims006 » Mon Dec 16, 2019 2:42 pm

I've done the chalk test, im getting the same contact patch results at 55psi that I am at 45psi - am I doing something wrong? What are yall running your pressure at? The lower I go, the worse mpg I am getting.
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verdesardog
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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by verdesardog » Mon Dec 16, 2019 2:56 pm

I tried the chalk test with nonsense results so I just go by the tire load chart.
Unloaded front 45psi, rear 35psi with 315-70-17's on a Cummins 2500.
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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by Bill2014 » Mon Dec 16, 2019 6:02 pm

Chalk test :lol:
Everyone's use case is different. I still wear my front tire edges about 1mm faster than the middle at 65psi on the Power Wagon. (Stock rim width and tire size)
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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by DamageWagon » Mon Dec 16, 2019 11:40 pm

Start high and work your way down. If you get the same patch at 45 and 55 it is because you’re already at full contact at 55 and need to go higher until you lose contact. At the point you get full contact, drop the pressure a few pounds to share the load across the tread, and run that and see how it wears over time.

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SimonandSimonBeast
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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by SimonandSimonBeast » Tue Dec 17, 2019 12:20 pm

I just went through this with a new set of tires. Different trucks, different tire brands, different tire sizes, different tire types (AT, MT) will all yield different results. I do think it is the best way to validate if you are running correct tire pressure for your given set up. I actually started doing a video when my phone decided to stop the video halfway through and then it proceeded to rain. If they are new tires I suggest doing this again in a few weeks after they break in, and maybe run them around town a bit before you do it to warm them up a bit. As an example, I'm running Toyo MTs 37x13.5 R17. I started them at 35 psi all around when they were brand new and they all chalked out OK with more chalk reveal on the lighter rear end, and less in the front. After a few weeks I checked again with the same results in the rear, so I am leaving the rear at 35 lbs (~1.5" chalk reveal). At the front I had almost zero chalk reveal and could see some outside shoulder lug wear. I went up 5 psi which had no or little effect on the chalk reveal. I went up another 5 psi (10 total psi) and acheived about an inch chalk reveal. So, I am leaving there for now at 35 rear and 45 front. Again, this is what is working for my rig and tire combo. Do your own test. It is my opinion that some amount of chalk is left, around an inch to 1.5 inches depending on your tire and tire width, so that you not prematurely wearing your other lugs and not too much reveal that you are wearing your center lugs.

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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by TommyDuncan » Tue Dec 17, 2019 6:01 pm

SimonandSimonBeast wrote:
Tue Dec 17, 2019 12:20 pm
I am leaving there for now at 35 rear and 45 front.
I've had these same tires for a couple of weeks in all different conditions and seat of the pants has me at the same pressures as you. I will do a chalk test eventually...

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SimonandSimonBeast
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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by SimonandSimonBeast » Tue Dec 17, 2019 7:09 pm

TommyDuncan wrote:
SimonandSimonBeast wrote:
Tue Dec 17, 2019 12:20 pm
I am leaving there for now at 35 rear and 45 front.
I've had these same tires for a couple of weeks in all different conditions and seat of the pants has me at the same pressures as you. I will do a chalk test eventually...
Good to hear. Sounds like I (we) got it right.

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Re: Geolandar 35's chalk test: what are you running your pressure at?

Post by cb1987 » Tue Dec 17, 2019 10:50 pm

this was some months ago and cant remember air temp but did chalk test on 35x12.5 18 E with 40psi on all four. front was good pattern. rear was slightly overinflated by probly 5psi

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