Does increasing wheel track width make much difference to body roll and safety?

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repo

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If you add to 2 inches width with 4.5" backspace wheels how much difference does it make with the likelihood of rolling during an emergency maneuver or whatever?
 
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That is a very difficult thing to quantify but from personal experience, running a wider track and heavier (wider) tires makes a very noticeable difference in the handling of the vehicle. The tires are the lowest point on the vehicle so while added rotational weight has a whole list of negative side effects, one positive trait is that they will lower your center of gravity. I ran a set of 31" winters with Tacoma wheels with the 5.25" (?) backspacing last winter and the handling suffered substantially.

I don't think 4.5" backspacing wheels (I assume 8" wide) on their own will make a huge difference over the stock wheels, but combine that with wheel spacers and/or heavier tires and they will.

But enough about all that safety stuff. Don't forget the most important part: Wide tires just look mean!
P1090259 by Brandon Faliszewski, on Flickr
 
A wider stance is a wider stance, but how the body rolls on the suspension is not affected the same way that overall stability is by widening your track width unless you limit body roll in the process.
 
repo said:
If you add to 2 inches width with 4.5" backspace wheels how much difference does it make with the likelihood of rolling during an emergency maneuver or whatever?
Click to expand...

If you're pairing that with a lift, you're essentially negating any gained stability as you've just heightened your center of gravity.

Many other factors come into play. Type of tire, height of sidewall, sway bars, armor, etc.

But if we're strictly talking about changing the backspacing of stock wheel size and/or adding wheel spacers, then I guess in theory you'd be gaining some stability, but your wheel bearings and ball joints are going to hate you.

Take this as an example.
Slap a pair of roller blades on your feet. Stand up, roll about. Feels pretty good and stable right (not factoring in your own ability/skill)?

Now, take those same rollerblades, remove the "blade" of wheels, build a bracket that pushes the mounting point of those "blades" outwardly by 2".
The blade is no longer directly under the middle of your foot. You've just shifted all of your weight to the outer edges of your feet.

Do you think you will feel more stable or less? If your ankles had the strength of Hercules, it could be a none issue, but I bet you'd actually feel less stable because of the stress you are now putting on your ankles.

I dunno if my analogy makes sense to you, but my point is that yes, having a wider track in theory is more stable and gives you better handling, but to take full advantage of that, the proper way to do it would be to extend the whole control arm and spindle assembly in the front and run a wider diff in the back.
 
BrandonF said:
I don't think 4.5" backspacing wheels (I assume 8" wide) on their own will make a huge difference over the stock wheels, but combine that with wheel spacers and/or heavier tires and they will.
Click to expand...

Arent stock wheels 4.5" bs?
 
octanejunkie said:
A wider stance is a wider stance, but how the body rolls on the suspension is not affected the same way that overall stability is by widening your track width unless you limit body roll in the process.
Click to expand...

Yes, this... ^

A while back I went from OEM wheels to OEM wheels plus spidertrax spacers which added about 2.5" of overall track. I personally felt the vehicle was more planted in corners but not really much more. However, I don't believe and didn't notice it impacting body roll. A stiffer sway/anti-roll bar would help, and/or stiffer springs, with controlling body roll itself.

My experience is anecdotal though, and not at all scientific. It's just what my butt told me after I put spacers on.

I do imagine though that additional track would help with off-camber driving and a potential roll over event, in some conditions.
 
SpidermanGeek said:
Take this as an example.
Slap a pair of roller blades on your feet. Stand up, roll about. Feels pretty good and stable right (not factoring in your own ability/skill)?

Now, take those same rollerblades, remove the "blade" of wheels, build a bracket that pushes the mounting point of those "blades" outwardly by 2".
The blade is no longer directly under the middle of your foot. You've just shifted all of your weight to the outer edges of your feet.

Do you think you will feel more stable or less? If your ankles had the strength of Hercules, it could be a none issue, but I bet you'd actually feel less stable because of the stress you are now putting on your ankles.
Click to expand...

That makes sense. I did a lot of research before I added spacers because I never ran them before & the consensus was that under 1.5" has minimal effect on the wheel bearings. (OEM, Koyo) I'm sure cheap bearings wouldn't last.
 
Having a wider track width by an inch or two will not make a big difference from a suspension geometry point of view but it will increase lateral stability some. However you are also changing scrub radius which effects the "nimbleness" of the tuck in quick maneuvers and can cause understeer.

Lifting the vehicle is where you can dramatically effect body roll around corners and during evasive maneuvers because when you lift a truck, you are changing the roll center. Roll center is not something I'd like to describe in words. It's much easier to see with a diagram. But basically, to the OP, your question is about roll center so if you'd like to learn more about it that's what you should google.
 
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repo said:
If you add to 2 inches width with 4.5" backspace wheels how much difference does it make with the likelihood of rolling during an emergency maneuver or whatever?
Click to expand...

Body roll wouldn't be affected by track width, but the propensity for the vehicle to rollover would be. Static stability factor, used by the NHTSA as a factor to estimate rollover propensity, is simply average track width divided by two times the height of the center of mass of the vehicle. Thus, increasing track width by 3% (arbitrary number) would increase this stability factor by 3%. As noted in another reply, adding tire mass would also decrease the height of the center of mass.

Track width is usually measured from the center of the tires so wider tires alone wouldn't technically change that part of the equation (spacers or a backspacing change would), but I would expect the effective track width for the purposes of rollover resistance to increase slightly depending on tire stiffness/pressure/size/etc.

I personally would rather trust my LBJs a little more and not increase my track width.

refs:
https://www.me.utexas.edu/~longoria/VSDC/09_vehicle_roll_dynamics_and_control/09_1_Vehicle%20Rollover%20Dynamics%20and%20Controls.pdf
https://one.nhtsa.gov/cars/rules/regrev/evaluate/809868/pages/IntroBack.html
 
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