16" Nomad Convoy on PZJ70 (1 Viewer)

[Sundowner]

My apologies. I misread your post to be honest. I am just curious how you adjust the backspacing accordingly to the scrub radius.

Short answer: you mock it up or diagram it out as best you can. I usually do mockups and then diagram it, because I'm good at getting things wrong the first time around.

Better answer: scrub radius is the difference between the contact point of the kingpin axis and the center point of the tire contact patch; as the tire grows in diameter, the kingpin axis' contact point moves further and further outboard, because triangles. If the center of the contact patch of the tire doesn't move outward as well - i.e. no change in backspacing - the scrub radius will increase... because triangles, again. Doesn't matter if you have a wide or narrow tire, in that case; there will still be a change in scrub, and the center point of the contact patch will be effectively identical between tire widths.

And all of that may mean exactly nothing; I'm too new to Toyota steering geometry to even pretend that I know anything about it.

 

[Sundowner]

The reason for proper back spacing/needing spacers when not using proper back spacing has to do with the wheel hitting steering links or not.

Or the frame, or shocks, or springs, or swaybar links, or sheetmetal, or etc, etc etc.

Back spacing and wheel width also affects the travel of the tires, as in if the whole assembly pushes the tire/wheel out the tires may hit parts of the fender that with proper spacing doesn’t. Don’t know if this is what you are asking.

Correct, but I usually get in trouble with other bits before I hit the sheetmetal...but that's because I don't know what I'm doing; especially not with leaf springs.

 

[blastronaught]

I have 15" Nomads on my HZJ73 with -10 offset. No spacers were required. The wheels are some of the lightest for the price on the market at only 17 pounds.

Damn, with all of this said about the Toyota OEM fitment while maintaining the holes rather than spokes, then I'm back to the Nomad (convoy). Roverdude, what size tire are you rockin' on the 15" then? I'm sold on this route.

Will report back with how things go.

 

[blastronaught]

Short answer: you mock it up or diagram it out as best you can. I usually do mockups and then diagram it, because I'm good at getting things wrong the first time around.

Better answer: scrub radius is the difference between the contact point of the kingpin axis and the center point of the tire contact patch; as the tire grows in diameter, the kingpin axis' contact point moves further and further outboard, because triangles. If the center of the contact patch of the tire doesn't move outward as well - i.e. no change in backspacing - the scrub radius will increase... because triangles, again. Doesn't matter if you have a wide or narrow tire, in that case; there will still be a change in scrub, and the center point of the contact patch will be effectively identical between tire widths.

And all of that may mean exactly nothing; I'm too new to Toyota steering geometry to even pretend that I know anything about it.

Sundowner, you've done some homework. Here is the treatise that was my foray into suspension tuning, if anyone wants additional reading on the topic.

The Ultimate Handling Guide Part 8: Understanding Your Caster, King Pin Inclination and Scrub - Page 5 of 6 - MotoIQ

, Increasing the scrub radius too much can cause wheel fight and twichyness under braking, especially on split friction surfaces and more sensitivity to bump steer. An extreme amount of…

motoiq.com

I do wonder if big truck rock crawlin guys really care much about scrub radius. I could see it being more of a finesse thing on tuned sports cars that doesn't matter much on big sloppy leaf springs bouncing all over the place... at least within reason. If it gets too wild it probably would create a hell of a moment arm and rip your thumbs off at the steering wheel (maybe?).

 

[FJ73Texas]

If you really want steel wheels with the look you desire. You can run these non US spec hilux 17" steel wheels. I have a part number somewhere but they are not easy to get here. @Honger runs the same wheels.

Here they are on my former PZJ70 that I owned. No spacers.

 

[jayp2]

The Nomads should fit fine in wheel well without any contact on steering parts

My 77 came with a set but the brain surgeon that put them on used a standard set of lug nuts that fit the wheels....which meant there were about 3 full threads of enguagement....no bueno

Problem is that the studs for the lugs are rather short and not specd to handle thicker allow wheels.

Solution is to go with steelies OR source out ET lug nuts that will fit

ET = extended thread

 

[blastronaught]

If you really want steel wheels with the look you desire. You can run these non US spec hilux 17" steel wheels. I have a part number somewhere but they are not easy to get here. @Honger runs the same wheels.

Here they are on my former PZJ70 that I owned. No spacers.

View attachment 3474369

Oh man.... that's the ticket!

 

[Tennessee Jed]

I'm confused - what's a US spec Hilux? I love those wheels, that's what I would have wanted. They look an awful lot like the 17" FJ Cruiser steel wheel.

 

[FJ73Texas]

I'm confused - what's a US spec Hilux? I love those wheels, that's what I would have wanted. They look an awful lot like the 17" FJ Cruiser steel wheel.

I had typed “non US” spec. I could have done a better job stating what I meant though. They come from European hilux I believe. I had gotten them from @joekatana but I don’t think he sells or brings them in anymore.

 

[Tennessee Jed]

Ah, okay - that's a bummer. That would scratch a lot of itches if that wheel was available.

 

[Sundowner]

I do wonder if big truck rock crawlin guys really care much about scrub radius.

Most don't.

I could see it being more of a finesse thing on tuned sports cars that doesn't matter much on big sloppy leaf springs bouncing all over the place... at least within reason

Forget the springs and everything else for a minute; just think about a mounted 35" tire - ideally on one of those dope steelies that we can't get - sitting upright on your garage floor, with no load on it. Think about how much effort it takes to spin it around its Y-axis, which is the center of the contact patch; it won't take much, will it? It also won't take much effort to roll it somewhere, because that's what it's designed to do...but if you try to shove it in any direction without rolling it, you've got an entirely different problem on your hands. The amount of force needed to make it skid sideways is incredible, compared to the negligible forces involved in the other two motions...and - again - this happens because that's what it's designed to do.

Now...put about 1000 pounds of weight on that tire, and do all of the same movements. It'll roll easily, pivot on its Y-axis/contact patch with some reluctance, but it isn't going sideways without rolling without a LOT of coercion. That, in a nutshell, is the entire point of tire design at play...and that's why the bigger the forces get, the more we might want to pay attention to them. Sure, you can generate a lot of force with speed in a sports car, but you can do it just as easily with weight in a big off-road tire.

If it gets too wild it probably would create a hell of a moment arm and rip your thumbs off at the steering wheel (maybe?).

Or pull a TRE apart. Or a ball joint. Or a kingpin. Or a steering gear. Scrub can definitely destroy parts along with handling qualities; it's one of the reasons that the wide-tired brodozers wear out ball joints so rapidly. Thus, I tend to look at backspacing pretty closely when I alter the wheel and tire from what the factory supplied me with.

Apologies for the derail; I'll be quiet now and go back to trying not to buy wheels, having now seen several sets that I like.

 

[Sundowner]

Okay, I lied: not being quiet yet.

Ah, okay - that's a bummer. That would scratch a lot of itches if that wheel was available.

I'd love a wheel option that might allow larger brakes, but I'm not too happy about the idea of R16 tires and their universally-too-stiff sidewalls. 17's would handle that.

 

[barrett1]

I have 15" Nomads on my HZJ73 with -10 offset. No spacers were required. The wheels are some of the lightest for the price on the market at only 17 pounds.

@RoverDude ,

Did you have to install extended studs as @jayp2 eludes to above. I looked at your build thread and didn't see you note this.

Sean

 

[Fishbulb]

Technically you should..... I read on here somewhere that 8 threads should be used for safety. The Nomads wheels allow skinny tuner style lugs to use 5 threads. If you got ET style lugs it might get you closer back to 8.