Up for new tires contemplating 39s

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PorterW1111

PorterW1111

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you're going to be able to go faster, hit bigger holes and hit them harder. Combine all of this together and you're going to need more fluid volume and valving. The dynamics of the larger tires are also going to beg for the extra control that the secondary bypass offers.

It isn't just about the tire weight. If anything, tire weight would kinda come in last place for the "why".

The only rigs on 39s that I've seen NOT run a secondary bypass are substantially lighter trucks or rock crawlers.


Feel like there is always a “it would be better with” when it comes to anything we do to these trucks. Put on long leafs, 4 link is better, buy 3.0 shocks, 4.0 are better. I agree with you new lca, secondary’s, and from bumps+limits would do the truck good, especially with 39s.

But with this iteration of the build the goal is focused on fitting 39s getting as much travel as I can get and having full steering. Also hopefully give others hope in choosing to run 39s as well.
 

zombiekiller

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Feel like there is always a “it would be better with” when it comes to anything we do to these trucks. Put on long leafs, 4 link is better, buy 3.0 shocks, 4.0 are better. I agree with you new lca, secondary’s, and from bumps+limits would do the truck good, especially with 39s.

But with this iteration of the build the goal is focused on fitting 39s getting as much travel as I can get and having full steering. Also hopefully give others hope in choosing to run 39s as well.

it was a bit of a feat to get KR3s on my truck while retaining all of the travel and being able to go to full bump through the full steering motion without interference.

It can sometimes feel like it always "would be better with", but my comment was actually more about making the front and gear suspension "match" in capability, along with supporting the size of tire.

Based on my experience and seeing what is working/not working on Baja runs, I've come to my own conclusion, which is:

Upgraded coilover & RXT shocks or Shock through the bed: 35s/37s

Upgraded coilover/secondary bypass & Shock through Bed: 37s/39s

Mid-travel kit & short course links : 37s/39s/40s

Long travel kit & back half: 39s/40s


I think that these are the setups that "match" .

I run 40s. I run a mid-travel kit. I run leafs, bumps and 4.0s through the bed.

IMO the rear suspension of my truck has a really hard time keeping up with the mid-travel kit. Ideally, The mid-travel kit should probably be paired with a short course setup.

I run leaf springs because They are cheaper to maintain and I break less "stuff". The leaf springs also keep me from being tempted to go Full HAM on the runs down south.

anywho, that's my take on it. Just my $.02. Depending on wallet, driving skill, terrain, load out, intended use, etc etc etc, what "works" and what "doesn't" constantly changes.
 

zombiekiller

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The OEM F150 Brakes will be out gunned by the weight of the 39's.

I suggest that you upgrade to Alcons, RPG or other BBK that fit.

I think the stock brakes were fine for short distance type of stuff, like some of the offroad park raptor "events".

Alcons are a HUGE improvement on Baja runs. They stop better, don't fade at all and generally inspire confidence. I think Alcon brakes are the best improvement that you can make, second only to bypass shocks on all four corners.
 
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PorterW1111

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The OEM F150 Brakes will be out gunned by the weight of the 39's.

I suggest that you upgrade to Alcons, RPG or other BBK that fit.
Good point. I did just put on new drilled and slotted rotors and pads all the way around. Will see how they hold up, when they burn up I’ll go bigger/better.
 
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PorterW1111

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More parts are here. Now just waiting on new tpms sensors and advanced fiberglass fenders to get here...

97D64A35-8CB9-4F83-BF69-F6F055F8E1BE.jpeg
 

zombiekiller

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i went through the same thing. Just take your time and check full bump eleventy billion times.

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The KR3s are 1.75" taller than the 39" KM3s, so at least you arent trying to stuff these in there. (yes, the "small" tires are 37" general grabber x3s. )
 
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