NDT tire pressure |
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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Posted: 24 Apr. 2018 at 10:44pm |
I have 6 ply (load range C) 7.00x16 NDTs on my '48. On the side of the tire it's says 45psi max at 1900lbs. That seems like way too high for this light little jeep that may have 600 - 700lbs on each wheel. I currently have them at 25psi for around town highway use. Does that seem about right? If not, what do you recommend?
Thanks, Steve
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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Jerry45
Member Joined: 29 Apr. 2007 Location: Cheshire, CT Status: Offline Points: 868 |
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KI run my NDT's at about 12 PSI. It helps with shock absorbing. I filled them up to the rated 32PSI once. Teeth rattling ride!!
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1945 CJ-2A #11802
1950? Szekley Navy APU Jeep Bantum BTC-3 Trailer "They can have my Jeep when they pry it from my cold, dead hands." |
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smfulle
Member Sponsor Member Joined: 16 Sep. 2010 Location: Ogden, Utah Status: Offline Points: 6123 |
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25 psi seems to work pretty well for me on the street. Jerry’s 12 psi is a lot softer, but I don’t like how squishy they feel in corners at speed when they are that soft. On the trail I run them at 8-9 psi. Makes a big difference in ride comfort and traction.
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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Thanks guys, glad to hear I'm in the right ballpark. I might try 20 psi to see how it feels. My thinking is that 20 might allow just a little larger contact patch with the pavement, and thus a tad more traction for braking.
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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oldtime
Member Joined: 12 Sep. 2009 Location: Missouri Status: Online Points: 4139 |
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I feel that street tire pressure is an important issue unless you simply don't care about tire wear.
You're right, these little jeeps are all just about over kill concerning tire load ratings. What one needs to do regardless of chosen tire is to get the tire inflated for the specific load that it will carry. In the end, what you are seeking is even tire wear. This implies that the full width of tread must contact the road. It's not hard to determine specific air pressure for your tires. Place loaded vehicle on a dry, flat, smooth, non slick cement surface. Wet a portion of the tire tread down with a sponge. Roll the wetted tread across the dry cement. The tread contact patch will show up as you roll the jeep across the flat. Start at high pressure (maybe 32 PSI) and then lower tire air pressure till you achieve a full contact patch pattern. Most skinny jeep tires will come into full contact patch pattern somewhere around 25 PSI.
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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Good idea Ken, thanks.
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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athawk11
Member Joined: 18 Jan. 2012 Location: Arvada,Colorado Status: Offline Points: 4145 |
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I like 25 PSI for NDCCs...around town.
16 PSI when we are on the trails. Frankly, I get a little nervous with the pressure down as low Stan. That said, he does have Rank on me out in the wilderness.
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1- 1946 CJ2A
2- 1949 CJ3A |
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smfulle
Member Sponsor Member Joined: 16 Sep. 2010 Location: Ogden, Utah Status: Offline Points: 6123 |
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Not sure about rank. Some added information. On our last little jaunt up Cliffhanger I got a flat tire. Haven't checked it out fully yet, but it looked like the valve stem might be cut. Don't know if running at 9 psi let the tire slip a little on the wheel and cut the stem, or if it was just one of those things. With the help of my trail mates I was able to swap the spare over in just a few minutes and off we went. |
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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It rained a little while ago, so I backed the jeep out onto the wet driveway and back into the garage. Looking at the wet track and wetness on the tread, it seems 25lbs may be too much. It does not appear that the full tread width is making contact. I assume full tread contact is optimal?
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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oldtime
Member Joined: 12 Sep. 2009 Location: Missouri Status: Online Points: 4139 |
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Just my opinion but....Yeah I think you need more contact than that.
Or else you'll just just end up running the center off the tread. The bigger the tire and a stiffer ply = greater load rating. The bigger and stiffer it gets the lower your PSI needs to be. It's kinda hard to tell when NDCC tires get full contact so try to get 5.5 to 6" of tread on the ground. I looked up STA NDT and NDCC 7.00 x 16" are supposed to be 5.8" tread width. Try maybe 22 or 23 PSI..... |
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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I repeated the test today, but dropped the pressure from 25 to 20. This gives notably better surface contact. 25 on top photo, 20 below. I'm hesitant to go any lower for street driving, I don't want it to get mushy in the turns.
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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oldtime
Member Joined: 12 Sep. 2009 Location: Missouri Status: Online Points: 4139 |
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Yeah, 20 PSI definitely looks like full tread contact..
Don't go any lower on pavement than what it take to achieve full tread contact.
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Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963) Zero aftermarket parts |
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Ol' Unreliable
Member Joined: 25 Sep. 2016 Location: CO Springs CO Status: Offline Points: 4226 |
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You might want to experiment with the Jeep unloaded, fully loaded (whatever that might mean for you) and in-between, just to obtain full data. Make a chart, keep a record. Thomas Jefferson would love it.
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There's a reason it's called Ol' Unreliable
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ndnchf
Member Sponsor Member x 2 Joined: 22 Sep. 2017 Location: Virginia Status: Offline Points: 2177 |
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I took it out for a nice test drive today. It handled and felt just fine. I did notice a little more tire noise. It wasn't objectionable, but I could hear it. 20psi seems to be the sweet spot for this set up
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1948 CJ2A - It goes nowhere fast, but anywhere slow.
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