Cooper or Maxxis?

[TankerZak]

But your saying the 37x13.50R17E had a softer sidewall than the 37x12.50R17D? That literally blows my mind...

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Not exactly. It was a result of a few things working together. The sidewall itself is not "softer."

The sidewall on the x13.5 is very durable/thick.
The x13.5 weighs 6-8 lbs more than the x12.5 and requires more PSI to take excessive flex out of the sidewall.
It has been a little while since I had the x13.5s, but I remember 3 things about them.

First, at full inflation, the rear tires did not maintain full contact with the pavement. They would ride on the center of the tire unless I added a considerable amount of weight to the bed. This led me to reducing the PSI until I had a good contact across the entire tread.

Second, at that level of inflation, I could feel the sidewall flex when applying power while cornering, during hard breaking, and during acceleration. It is hard to describe if you haven't felt it, but the flex was significant enough at times that it made me feel like I was about to slide. At other times you could feel it like a long "slap" coming to rest as the flex came out of the system.

Third and last, running at the pressure that afforded the good contact pattern also allowed a lot of bounce that the shocks really could not address.

I am not having the contact pattern issue with the x12.5's at any inflation pressure up to max, nor the sidewall flex issue, nor the bounce issue.

I actually preferred the x13.5's based on the dimensions, which is why I bought them initially.
Going to the x12.5 gave up a little in the tread width and ply rating.
At the same time though, I picked up a slightly narrower track and turn radius, reduced tire weight resulting in more responsiveness, and higher max load (load actually goes up by 300+ lbs per tire).

My truck is now just low enough and narrow enough that I can still use my unlimited automated car wash membership in the winter to keep the road salt off of it every day.

Interesting. I like the idea of the 13.5 being squishier when I need it to be. Only time my tires are at max PSI is when they are towing and have 1300lbs in the bed (tounge weight). Rest of the time they hang out at max contact patch PSI.

You said the shocks couldn't keep up. Are you still on stock shocks? Just asking because I'm on King 3.0/2.5s so that might not matter for me. But now that your mentioning it I should go check with my carwash... lol.

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[Jack187]

I'm still on stock shocks through all 3 sets of tires. I like trying things "outside the box" occasionally to see what I can do with them.
I went to the STTs within the 1st month they were released with the new tread pattern.
It took me a few tries with various configurations, but I eventually found what I was looking to achieve.

Another thought on the x13.5s..... I think it is probable the sidewall issue wouldn't have occurred if I had used a wider wheel.
Because I chose to use the 8.5 Katla on such a wide tire, I think it likely amplified my issues.
If I had gone with the 10" Katla (or some other 10" wide wheel), I don't think the tread contact issue nor flex issue would have occurred to the same degree, if at all. Unfortunately, I couldn't locate a 10" wide wheel with the same overall alignment I can get with the 8.5 Katla.

One of the things I strove to do was keep the wheels/tires under the truck. It kept my options for parking/car washes/etc... as wide as possible.
The factory Powerwagon wheels apparently have a 6" backspace on an 8" wheel. The Katla was the next closest I could find to that spec.

If you are going with a wider wheel, the x13.5s might be the ticket for you.

[Colibri]

But your saying the 37x13.50R17E had a softer sidewall than the 37x12.50R17D? That literally blows my mind...

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Not exactly. It was a result of a few things working together. The sidewall itself is not "softer."

The sidewall on the x13.5 is very durable/thick.
The x13.5 weighs 6-8 lbs more than the x12.5 and requires more PSI to take excessive flex out of the sidewall.
It has been a little while since I had the x13.5s, but I remember 3 things about them.

First, at full inflation, the rear tires did not maintain full contact with the pavement. They would ride on the center of the tire unless I added a considerable amount of weight to the bed. This led me to reducing the PSI until I had a good contact across the entire tread.

Second, at that level of inflation, I could feel the sidewall flex when applying power while cornering, during hard breaking, and during acceleration. It is hard to describe if you haven't felt it, but the flex was significant enough at times that it made me feel like I was about to slide. At other times you could feel it like a long "slap" coming to rest as the flex came out of the system.

Third and last, running at the pressure that afforded the good contact pattern also allowed a lot of bounce that the shocks really could not address.

I am not having the contact pattern issue with the x12.5's at any inflation pressure up to max, nor the sidewall flex issue, nor the bounce issue.

I actually preferred the x13.5's based on the dimensions, which is why I bought them initially.
Going to the x12.5 gave up a little in the tread width and ply rating.
At the same time though, I picked up a slightly narrower track and turn radius, reduced tire weight resulting in more responsiveness, and higher max load (load actually goes up by 300+ lbs per tire).

My truck is now just low enough and narrow enough that I can still use my unlimited automated car wash membership in the winter to keep the road salt off of it every day.

Interesting. I like the idea of the 13.5 being squishier when I need it to be. Only time my tires are at max PSI is when they are towing and have 1300lbs in the bed (tounge weight). Rest of the time they hang out at max contact patch PSI.

You said the shocks couldn't keep up. Are you still on stock shocks? Just asking because I'm on King 3.0/2.5s so that might not matter for me. But now that your mentioning it I should go check with my carwash... lol.

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I’ll agree with pretty much all of jacks observations on 13.5’s but I intentionally run 13.5’s on a less than 10 inch wide wheel because I want the squish.

TankerZak you have plenty of shock! No issue there at all. Not sure what valving you have, or how you drive and use your truck, but if you like to boogie a little you’ll find the wider tire is much nicer in combination with your kings. When you air down the tire will soak up all the small chatter and washboard etc and really smooth the ride out. Think of tires as part of your suspension.

I use my truck for work and towing as well, and it’s completely fine as long as you adjust the pressures accordingly. But daily driving my pressures are fairly low for max contact pattern and there is some squirm from it. For me it’s an easy trade off, but apparently it’s not for everyone

[Jack187]

I’ll agree with pretty much all of jacks observations on 13.5’s but I intentionally run 13.5’s on a less than 10 inch wide wheel because I want the squish.

TankerZak you have plenty of shock! No issue there at all. Not sure what valving you have, or how you drive and use your truck, but if you like to boogie a little you’ll find the wider tire is much nicer in combination with your kings. When you air down the tire will soak up all the small chatter and washboard etc and really smooth the ride out. Think of tires as part of your suspension.

I use my truck for work and towing as well, and it’s completely fine as long as you adjust the pressures accordingly. But daily driving my pressures are fairly low for max contact pattern and there is some squirm from it. For me it’s an easy trade off, but apparently it’s not for everyone

Colibri nailed it.

[Jack187]

Hey Jack, how about some pics of your setups?! Seems like I came across a few on aev forum long ago, but nothing else. Nice looking rig for sure! And thanks for your reviews!

Here are a few pics I promised. My truck is pretty basic. It's a Tradesman with the PW option. I'm an older guy and still have fond memories of the 4 wheel drives of the 80s. My choices are somewhat retro. My front and rear bumpers are both relative throwbacks to what was popular in West Texas back in the day.

I'm now in the Milwaukee Wisconsin area. Not much rock nor dunes around here. Most off-roading consists of snow, grass, forest, and bogs.

My front bumper allowed me to keep my factory winch and fair lead intact. I rarely run it with the hook attached unless I am going to use it, because people in the immediate area seem to like to steal anything not welded in place (like my first hook). The winch is tension-ed with synthetic line against the factory fair lead with a rubber detente running through the eyelet. To use the winch I just release the tension, feed it through the second fair lead, and add the hook. The top of the bumper opens to allow access to the winch for use/maintenance.

Most of my mods are rather simple. I added a Dethloff rack, a Bak bed cover, Magnaflow HD50 muffler (adding a J-Pipe to tune it next week), rear backup lights, locker bypass and nanny, aux power switches, and misc other things. I'm all about keeping things "simple". Here shortly, I'm going to swap out the shocks, add a Thuren rear track bar, and install my WK sliders that have been sitting in my garage. I picked up AlfaODB and fixed my speedometer just recently. Nice tool for those looking to fix your speedometer.

One last thing, before anyone bothers, I don't care if people can read my license plate. It's all good.

[olyelr]

Nice truck!!!! Thanks for the pics!