Tire size and wheelbase

[kmas0n]

@mrblaine
In the thread
Is this too much rust?
You posted:
"Yes, that is why they picked the length. Everything moves back exactly 15" to use the belt rails, top, and factory roll cage from a TJ Unlimited. The wheelbase is too long for 35's but I'm going to dink with it some after it is all done and see where I go from there."

It is not the first time I've heard you reference tire size to wheelbase. I was hoping you, or others could educate me (and others) on this. Is there a "correct" tire size for a set wheelbase? what are the determining factors? Tire clearance aside is there an optimal lift height for a certain tire size?

 

[mrblaine]

@mrblaine
In the thread
Is this too much rust?
You posted:
"Yes, that is why they picked the length. Everything moves back exactly 15" to use the belt rails, top, and factory roll cage from a TJ Unlimited. The wheelbase is too long for 35's but I'm going to dink with it some after it is all done and see where I go from there."

It is not the first time I've heard you reference tire size to wheelbase. I was hoping you, or others could educate me (and others) on this. Is there a "correct" tire size for a set wheelbase? what are the determining factors? Tire clearance aside is there an optimal lift height for a certain tire size?

No, there is not a correct size tire and wheelbase balance with regard to frame heights. There are very clear examples of what works very well for certain regions. If you don't wheel in the same terrain, it won't apply.

For my area and type of wheeling which is rocks, big rocks and even bigger rocks on very technical trails, there is a well defined balance.

You start with a TJ on 35's with about a 19-21" frame height at 100ish WB. 37's are 104 WB with about 21-22" of frame height. 40's are 108" WB with 22-23" of frame height. This all assumes a raised belly skid flat to the frame rails with no more than 1.5" of drop at a narrow section in the middle. If you pay attention, the frame is not going up as high as the tire increase in size. As they go larger in tire size, the lower the center of gravity gets comparatively.

 

[kmas0n]

Thank you for your insight.

 

[billiebob]

No, there is not a correct size tire and wheelbase balance with regard to frame heights. There are very clear examples of what works very well for certain regions. If you don't wheel in the same terrain, it won't apply.

For my area and type of wheeling which is rocks, big rocks and even bigger rocks on very technical trails, there is a well defined balance.

You start with a TJ on 35's with about a 19-21" frame height at 100ish WB. 37's are 104 WB with about 21-22" of frame height. 40's are 108" WB with 22-23" of frame height. This all assumes a raised belly skid flat to the frame rails with no more than 1.5" of drop at a narrow section in the middle. If you pay attention, the frame is not going up as high as the tire increase in size. As they go larger in tire size, the lower the center of gravity gets comparatively.

very well said, where you wheel, what you do is key

 

[jjvw]

very well said, where you wheel, what you do is key

My sense is that these concepts carry through into different environments. What changes the most are the level of significance these ratios, balances and details have in whether or not a build is more or less capable within it's usual territory.

Meaning that a well considered Johnson Valley build is larger and more refined than what is necessary for most of Colorado. The full JV build is going to walk effortlessly though almost everything here. Whereas something like mine (even at the point of completion I have in mind, which is looking further West for inspiration) is going to find it's limits sooner in a tougher environment.

The fundamental ideas are the same, the degree of importance or even necessity is not the same.

 

[toximus]

My sense is that these concepts carry through into different environments. What changes the most are the level of significance these ratios, balances and details have in whether or not a build is more or less capable within it's usual territory.

Meaning that a well considered Johnson Valley build is larger and more refined than what is necessary for most of Colorado. The full JV build is going to walk effortlessly though almost everything here. Whereas something like mine (even at the point of completion I have in mind, which is looking further West for inspiration) is going to find it's limits sooner in a tougher environment.

The fundamental ideas are the same, the degree of importance or even necessity is not the same.

This is what I'm finding too. There are a few exceptions however and that is different tires work significantly better in some areas, an auto locker works fine in the front for JV but is unpredictable on snow and ice on the street, having no fender flares is king in JV (or any tight trail) but on wet trails (or in JV after a rain storm lol) this allows too much slop to cover your windows.

Aside from those things, I do think hardcore trails can help refine even a mild build.

 

[billiebob]

I'm speechless

 

[Bob.Gibson]

While I still have your attention Chris.
Do you know if a Hi-lift jack bracket off the rear door of a JK will bolt straight on to a TJ rear door?