Am I crazy? Higher PSI in 35's = better steering and handling overall - Jeep Wrangler Forum
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Old 02-05-2015, 08:44 PM
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Am I crazy? Higher PSI in 35's = better steering and handling overall

I keep reading that doing a chalk test is the way to go when setting the PSI for your tires. Most people doing this end up with a PSI in each tire around 26-28 PSI in 35's.

I just got my '15 JKUR back with a 2.5" RK X Factor mid arm kit, Fox (teraflex tuned) reservoir shocks, Fox ATS steering stabilizer, and 35x12.5x17 Nitto Trail Grapplers on Fuel Trophy wheels.

I aired down initially to 30 PSI on all 4, and noticed the steering likes to kind of wander around on the highway. Nothing bad, but I did notice the steering required more frequent input to keep it tracking in my lane.

I bumped the PSI to 37 and can barely feel a difference in firmness- then again I like that as I come from sports cars and even have a Tesla P85 with 22's on tiny 35 and 25 series tires that rides pretty firm.

What I did notice is that the handling is much better, less body roll (stiffer sidewall) and it tracks better on the highway. Sure its a tiny bit stiffer when hitting an even part of pavement or whatever- but I think its a big improvement over softer tires.

I really think lower PSI allows too much sidewall flex and too much contact patch allowing road imperfections and grooves to constantly move the jeep around when trying to drive in a straight line. Less contact patch and stiffer sidewalls seem to work for me, and I don't care about tire wear to be honest. I am used to changing tires at 10-12K miles so if they get at least that I am good.

Thoughts??

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Old 02-05-2015, 08:56 PM   #2
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I am running 35" nitto trail graplers at 30 psi , I also like a firm ride . I have very little body role and the steering is much less twichy at lower pressure imo.

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Old 02-05-2015, 09:17 PM
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I am running 35" nitto trail graplers at 30 psi , I also like a firm ride . I have very little body role and the steering is much less twichy at lower pressure imo.
Maybe my steering is less twitchy because of my stabilizer?

But have you noticed less "wandering" at higher pressures vs at 30psi? Where you need to constantly make minor corrections above 70MPH on the highway?
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Old 02-05-2015, 09:21 PM   #4
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To be honest I have not been driving 70 plus so I do not know I am still playing with my pressure. When I had the tires instaled the shop put around 60psi in them had very twitchy sreerngi reduced to 30 psi stereing seems better . I will have to try them at 37 psi. Did you install an after market stabilizer?
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Old 02-05-2015, 09:46 PM   #5
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Toyo MTs 34's run them at 36-38
I like the ride with them around there handles great might be on the rougher side to some
Air down to 10-15 off road
22k miles. Treads at 13-14/32
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Old 02-05-2015, 09:57 PM   #6
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Nope, you are not crazy!!!!!!!!!
I also prefer higher PSI for better handling, in my Wrangler and Escalade tires. I have owned my share of Corvettes, and also ran higher PSI, verses recommendation.
Plus you will enjoy more power, and better fuel economy.IMO

Tire chalking will give you the best tire wear, along with a smoother ride. IMO

Most on the Forum seem to like running lower than recommended PSI.
So there is no right or wrong, but rather a choice!!!!!!!
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Old 02-05-2015, 10:05 PM
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Originally Posted by Fla Tom View Post
To be honest I have not been driving 70 plus so I do not know I am still playing with my pressure. When I had the tires instaled the shop put around 60psi in them had very twitchy sreerngi reduced to 30 psi stereing seems better . I will have to try them at 37 psi. Did you install an after market stabilizer?
60PSI - wow! That's way too high so thats why you had that twitchiness I would imagine.

Also, yes I have a stabilizer- the Fox ATS which I am sure absorbs a little of that bump steer when running a bit higher PSI.

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Nope, you are not crazy!!!!!!!!!
I also prefer higher PSI for better handling, in my Wrangler and Escalade tires. I have owned my share of Corvettes, and also ran higher PSI, verses recommendation.
Plus you will enjoy more power, and better fuel economy.IMO

Tire chalking will give you the best tire wear, along with a smoother ride. IMO

Most on the Forum seem to like running lower than recommended PSI.
So there is no right or wrong, but rather a choice!!!!!!!
Makes total sense as I come from a Corvette background and also other sports cars - I definitely prefer the higher PSI too. Glad I am not nuts, seems no one runs higher PSI. When I was running 30-32 it just didn't feel right, might even be unsafe even lower than that- I am assuming much worse braking distance and even more chance of rollover in extreme movements as the tires flex too much from the soft sidewall (me just speculating of course)
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Old 02-05-2015, 10:56 PM   #8
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Higher pressure stiffens the sidewall (decreasing compliance) which tends to yield sharper steering, and may give the impression of sharper handling (though ultimately the handling may or may not be better). Think about it this way--when you turn the wheel, the sidewall "flexes" absorbing some of your steering input. The more absorbing, the less linear the feel. Ultimate handling depends on a lot of diverse factors.
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Old 02-06-2015, 12:21 AM   #9
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Higher pressure stiffens the sidewall (decreasing compliance) which tends to yield sharper steering, and may give the impression of sharper handling (though ultimately the handling may or may not be better). Think about it this way--when you turn the wheel, the sidewall "flexes" absorbing some of your steering input. The more absorbing, the less linear the feel. Ultimate handling depends on a lot of diverse factors.
but I would add the additional caveat that less PSI causes a wider skidpad for the tire, and allows the tire to roll more onto the sidewall when turning. When accelerating like a drag-racer, this is fine. Any deflection is in the direction of tire rotation. Tire tread is designed to interface the road. However, when turning, the tire deflects laterally - away from the turn. With less PSI and a wider skidpad, the tire starts to roll onto the sidewall. This is not ideal, as the sidewall uses different compounds and will not give good traction. In addition, as the tire starts to roll onto its sidewall, it starts puts less force onto the inner tread of the outside tire, and the tires start to slip. Each time it does, the tire starts to correct, it slips, etc. This oscillation happens quickly, and we hear it as a high pitched squeal when the tire is at the limit. So, lower PSI is great for drag racing and absorbing bumps offroad and drag racing, but it makes the tires perform sub-optimally when you apply lateral force. (i.e. turning.)
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Old 02-06-2015, 03:20 AM   #10
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The chalk test results in low air pressure on tires with a high load rating and stiff sidewalls like large AT and MT tires. Lower pressure in the tires causes more friction (slower handling and increased fuel consumption), degrades handling (more flex in sidewalls) and increases the tires tendency to grab onto irregularities on the road. That is a lot to give up just to maximize the tire tread footprint.
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Old 02-06-2015, 10:38 AM
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The chalk test results in low air pressure on tires with a high load rating and stiff sidewalls like large AT and MT tires. Lower pressure in the tires causes more friction (slower handling and increased fuel consumption), degrades handling (more flex in sidewalls) and increases the tires tendency to grab onto irregularities on the road. That is a lot to give up just to maximize the tire tread footprint.
Agreed 100%. I see a lot of "My jeep is wandering" threads and had the issue myself at lower PSIs.

Maybe they really need to look at the tire pressure- its great to have a nice full contact patch for better tire wear, but big off roading tires with a big contact patch will grab onto the grooves in the road and steer it all over the place. I am cool with worse tire wear at the expense of better handling, steering, MPG's etc.
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Old 02-06-2015, 06:46 PM   #12
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It is a tradeoff and always has been. Higher pressure for streetability, lower for off road. Most try to find the happy medium, or invest in an air compressor.

Bob K.
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Old 02-07-2015, 11:50 AM   #13
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It is a tradeoff and always has been. Higher pressure for streetability, lower for off road. Most try to find the happy medium, or invest in an air compressor.

Bob K.
+1

Lower PSI rides good but is squishy. Higher PSI rides less great but gives firmer handling. Coming from a sports car, you probably like the firmer ride. As long as your tread is making good contact, it's personal preference. I like my ride like I like my women...squishy

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