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Unread 07-03-2015, 08:50 AM   #1
mrdeezus
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2013 JKUR -Teraflex suspension very rough

I have a 2.5 inch TF lift with Bilsteins 5100 and Goodyear Duratracs(35s). The ride is rough on the street, where I mostly drive it. I have tried reducing the air pressure which helped a lot but it still is not as smooth as id like it to be. My air pressure is at 31 cold and 35 hot. My question is, is there any way to soften the ride with what I have?
I have been wanting to go to 3.5 inches but if I do I want a smooth ride that works both on and off road. Thanks for any suggestions...

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Unread 07-03-2015, 09:00 AM   #2
christensent
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Most people run 25-30psi in 35's, so you could try even lower. Ideally you would use the chalk method to figure out the correct tire pressure for your load for optimal tire wear.
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Unread 07-03-2015, 09:10 AM   #3
jwmbishop
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Puck lift or spring lift? The stock springs will seem harsher on a puck - changed the geometry without softening the rate.

If you reduce the max weight the tire sees - you reduce the PSi to carry that weight in the same ratio. Here's how the engineers (would) come up with your placard (cold) pressures (if using a load ranged tire instead of a load indexed tire). And do not bleed off the heat growth (glad to see you do check it though - its indicative of pressure min explained later)

That tire is a load range tire - 3195lbs at 65PSi. An Unlimited will put 1425 max weight on it (GVWR 5700/4).
3195-1425=1770 reduction in weight. 1770/3195=.55
65PSi reduced 55% is 29.25 PSi
Therefore your bare minimum PSI at 1425 is 30PSi.

Using curb weight (instead of GVWR) of 4300 lbs - its 1075 lbs @ 23PSi.

I use 1250 per tire when doing the math on my 4 door - hits right at 26.

SO there's your PSi range for that tire on your jeep. Find the PSi that balances ride to wear and stability. Usually mid way between the two - but ALWAYS go up to the PSi for GVWR when carrying a load at speeds over 55mph!

WHY is there a min PSi fort a maximum load (and why is the standard a cold PSi)? To balance heat dissipation. The lower the PSi the more heat the tire gains and retains. SO an underinflated tire will grow a larger percentage than a properly inflated tire. A tire could start at 20 and grow to 27, or start at 26 and grow to 29 (with far less treadwear and sidewall strain) on the same trip! This is what you see race teams doing when they pull a hot tire and start cleaning (to measure tread wear) and remeasure the circumference and temps - that way they know where to start PSi so that at the prime of the tires run - its right where they want it circumference and slip angle wise!
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Unread 07-03-2015, 09:31 AM   #4
mrdeezus
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spring
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Unread 07-03-2015, 09:56 AM   #5
jwmbishop
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Quote:
Originally Posted by mrdeezus View Post
spring
Run the tires down to 27 cold and see how that feels. I love my TF 2.5 springs on the road - but I have their shocks. I haven't played with any other shocks so wouldn't have a recommendation.
But if you cant get it smooth with the tires - that is your direction. Remember spring frequency is what makes it "feel" one way or the other. Shocks should be matched to get the freq as close to 1Hz as possible for best ride.
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Unread 07-04-2015, 08:06 AM   #6
Neo1130
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With my 35" Duratracs, there is a HUGE difference in 30 psi and 25 psi even. So I agree with the above to remove just a tad more air!
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