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View attachment 1461097 We bought our JK 4 dr. unlimited 70th Anniversary (Sahara) from the original owner with 305/50/20 tires on 20" rims (has a 2" lift). They look pretty sharp. I found that driving it at 45mph on our country paved roads requires two hands on the steering wheel because it seems the tires grab every small crease and bump in the road and causes the Jeep to all of a sudden jerk the steering one way or the other? One day I drove over a long pot hole patch and I almost drove off the road at 40 mph. We took a 200 mile trip last weekend on the interstate and any uneven pavement became really unnerving above 60 mph. My wife is scared to drive it except when we are on a Jeep trail. Would a skinnier tire and smaller wheel help us get the control back? And what size would you recommend?
 

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Yes, a skinnier tire would help. But a 305 tire isn't all that wide, so I suspect there is something else going on besides the wide tires. Get a front end alignment done. The castor is probably not in factory spec, and you may need adjustable control arms (if you don't have them) to get the front end back in line.
 

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Steering Stabilizer?????
 

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adjustable control arms or drop brackets, loosen and retorque control arms and track bars on a level surface, if your rear track bar is not level with the axle get a track bar bracket. alignment and re-balance tires. one of those i would bet will fix it.
 

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I went from my 2012 Sahara 18" P225/70R18S to 305/65R17 M&S. I just drove 1700km to Moncton New Brunswick from Hamilton Ontario no problems. Went through the States. 75mph. No shimmy or shake.
 

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Discussion Starter #10
Just to be clear....there is no shimmy or shaking. There is no death wobble. The Jeep just seems to want to follow any disturbances on the pavement. When on a nice flat paved road it drives perfect. But, drive on any paved road with asphalt patches, frost bumps etc. and the front wheels wants to follow the curves and imperfections. This especially becomes dangerous at higher speeds. I can't imagine fighting this on icy roads? So, I'll take it into a well respected shop in Spokane for a front end alignment and see if it fixes it. This shop is supposed to be very good with 4x4 rigs. I'll update the results.
 

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Tires are usually the cause of tramlining.

As above, what's your PSI at?
 

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Discussion Starter #12
I should also mention I just had a tire rotation and balance last Thursday with no change in the condition. The tires max PSI is 50. I'm running 40. I was running 35 but the TPMS light kept coming on. There was no change in the tramlining between 35 and 40 psi.
 

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Might want to try around 30 psi, not exactly sure what the actual diameter is, but 35-40 may be too high. Pictures of your front suspension/steering might help out too.
 

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It does sound like a case of tramlining but that tends to occur mainly to road tires. Your tires appear to have longitudinal channels for a smooth ride and less noise akin to a road biased tread. Off road tires are broke into blocks to provide a higher void ratio or edges to gain traction. When one of the edges of the channels locks into a groove or edge on the road/trail it can make the tire grip and release the grooves and make the vehicle shift back and forth slightly.

You can reduce this tendency by dialing in more stability via our old friend the Caster angle. As usual a stiffer stabilizer will just mask the problem. Lowering your PSI can also help because the sidewalls become more compliant and if you tires are "crowning" due to high PSI you will distributed the tire load across more grooves.
 

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I wouldn't be afraid to start at 26 PSI and go up from there...but I run my 33" x 12.5" Duratracs at 26PSI....granted smaller Jeep but still..........also I am sure if the rest of suspension work was not done correctly the tires running that high of TP will only make it worse.....GOOD LUCK!!
 

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Tramlining tends to occur with big wide tires that have stiff short sidewalls. I cant say for sure, but it looks like he is running Toyo or Nitto tires from the picture. They have short sidewalls (20" wheels), and I'll bet they are load range E.

Changing to a 285 width tire, with 17" wheels, and load range D would help.
 

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Tire pressure is my guess. My jeep did exactly the same thing with a set of Toyo MT. At 40 it was scary. Dropped to 29 and rides perfect now.
 

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Tramlining tends to occur with big wide tires that have stiff short sidewalls. I cant say for sure, but it looks like he is running Toyo or Nitto tires from the picture. They have short sidewalls (20" wheels), and I'll bet they are load range E.

Changing to a 285 width tire, with 17" wheels, and load range D would help.
We have a winner. Yes, the 50 profile, combined with the 305 width, is the issue. Try a 17 inch wheel, and 70 or 75 profile.
 

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Proper front end alignment would be my first guess. Larger tires and high tire pressure amplify the effect.
Even new JK's aren't known for having the correct amount of toe in from the factory.
They just get it close enough and call it good.
Both of my new JK's had to be re-aligned to track straight.
 
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