2010-13 vs. 2014-Up GX460 Turning Radius (1 Viewer)

[Rollover]

OK... I think I may have found it.

Starting in 2014 Toyota started specifying the turning circle as, "Wall to Wall" instead of "Curb to Curb" on the GX, but not the T4R.

A turning circle of curb to curb is going to be tighter than wall to wall. With wall to wall you start hitting the front fenders, maybe mirrors etc.

I suspect that all GX460's have the same real turning radius or circle, just the terminology changed.

This information comes from the official Toyota Product Information sheets put out by Toyota's PR department.

As always, I look forward to your thoughts.

 

[tortoiseracing]

OK... I think I may have found it.

Starting in 2014 Toyota started specifying the turning circle as, "Wall to Wall" instead of "Curb to Curb" on the GX, but not the T4R.

A turning circle of curb to curb is going to be tighter than wall to wall. With wall to wall you start hitting the front fenders, maybe mirrors etc.

I suspect that all GX460's have the same real turning radius or circle, just the terminology changed.

This information comes from the official Toyota Product Information sheets put out by Toyota's PR department.

As always, I look forward to your thoughts.

That would be a reasonable answer to this riddle. If all the steering components are similar on 2010 and 2014 vehicles, then if Toyota changes its measurement method, then it would still result in a change in turning radius. The location of the corner of the front bumper would dictate the turning radius.

Rollover, do you know if Toyota changed its measurement methods for the turning circle on other vehicles? Any idea why it did not make the change for the T4R?

 

[Acrad]

Overall length:

'14+ 460 - 192.1 inches

'10-'13 460 - 189.2 inches

'10-'14 4R - 189.9 inches

'15 -'19 4R - 190.2-191.3 inches

 

[Rollover]

That would be a reasonable answer to this riddle. If all the steering components are similar on 2010 and 2014 vehicles, then if Toyota changes its measurement method, then it would still result in a change in turning radius. The location of the corner of the front bumper would dictate the turning radius.

Rollover, do you know if Toyota changed its measurement methods for the turning circle on other vehicles? Any idea why it did not make the change for the T4R?

That's a good question and you wonder why only Lexus would switch from curb to curb (C2C) to wall to wall (W2W), and only on the GX.

I downloaded a bunch of "Product Information" sheets from Lexus. Below is a recap of what I discovered in regards to turning circle specs.

2012 RX W2W LX (NA) GX (NA)
2013 RX W2W LX C2C GX C2C
2014 RX W2W LX C2C GX W2W
2015 RX W2W LX C2C GX W2W

(NA) Not Available)

My guess is that some marketing genius at Lexus thought that there should be some consistency in the turning circle standard between the RX and GX, so they just added one meter to the C2C on the GX and called it W2W.

Spot checking various current Toyota models it's all C2C on the product information sheets.

A quick check of the steering components between 2013 and 2014 GX and the 2014 T4R showed no changes in steering components other than the stabilizer bar.

 

[Rollover]

Overall length:

'14+ 460 - 192.1 inches

'10-'13 460 - 189.2 inches

'10-'14 4R - 189.9 inches

'15 -'19 4R - 190.2-191.3 inches

22Eyunu35vo,

Interesting point. The curb to curb distance is unrelated to overall length, but wall to wall (W2W) could be affected by overall length, depending on where the length is.

All things being equal, W2W will increase as the distance from the center of the front tire to the outermost corner increases like it appears to on the 2014+ GX.

 

[Rollover]

22Eyunu35VO,

I'd go ahead and ask Lexus about it.... All they can do is say no.

 

[tortoiseracing]

I did some math, and if the way Toyota is measuring the turning circle has changed from curb-to-curb to wall-to-wall, then the difference in numbers makes sense. Here is how I interpret the measurements:

Curb-to-curb turning circle is measured at the outer front wheel.
Wall-to-wall turning circle is measured at approximately the corner of the outside front bumper (the farthest point from the center of the turning circle).

Here are the numbers I'm using:
Wheelbase = W = 109.8"
Overall Length = 192.1"
Front overhang = (192.1 - 109.8)/2 = 41.15" (this is an approximation)
Turning radius (curb to curb) = R = 38.1' / 2 = 19.05' = 228.6"

Using all those numbers and the diagram from this web page:

turning radius

Based on my calculations, the front wheel turn angle = alpha = 28.7 deg.
Then, I calculate the rear wheel's turning radius = r = 200.5"
Finally, the wall-to-wall turning radius ends up being 251.0" (not shown in the picture), which equates to a turning circle of 41.8'.
(Let me know if you want the math details for the previous calculations.)

Like I mentioned, I am approximating the front, overhang, and the bumper corners are rounded, not squared off. That's why my number (41.8') is larger than what Toyota reports (41.4').

I should also mention that if I calculate the front wheel turn angle based on the steering ratio (18.4:1) and steering wheel maximum lock-to-lock (3), I get a maximum front wheel turn angle of 29.3 degrees.

This results in a calculated wall-to-wall turning circle of 41.7' which is also close to Toyota's number.

 

[Rollover]

Tortoiseracing,

Great job doing the math. I think we solved the puzzle and you confirmed it. Considering that a stock GX could get hung up on many curbs... Measuring wall to wall is a more accurate real-world reality with any low hanging front end.

Thanks again,

 

[scmcna]

Any clue why the 2014+ GX460's have an increased turning radius? The T4R stayed the same.

From Toyota's product information.

2013 GX460 Turning Circle 38.1ft
2014 GX460 Turning Circle 41.4ft
It's almost exactly a meter difference (1.00584)

Is it a clearance issue with the newer front end? If you ditch the front bumper can you get the turning radius back to the 2013 specs?

Thanks in advance,

And the GX 470 is only 37.4 feet!

 

[MrTorgue]

And the GX 470 is only 37.4 feet!

Truth. Our 470 has a tight damn turning circle, much tighter than our 460.