0.5" spacer to widen track?

[RavenTai]

One issue. 1/2" on either side would add 1" total.

well adding 1/2" each side does increase the track/tread by 1" but what the math above is about is tipping over in that case you are on one tire, the other tire that is in the air is not doing much for you.

Picture a triangle formed between these 3 points
A. the outside corner of the tire (the pivot)
B. the center of gravity
C. the point where a line drawn from the center of gravity towards the center of the earth meets the surface of the driveway.

A. to C. is half of the measure from outside tire tip to outside tire tip or 42.3” stock, called a “side”
B. to C. is the height of the CG above the ground, I guessed at 30” also called a “side”
A. to B. is the hypotenuse

As soon as the line drawn from A. to B. passes through vertical you tip over.

So we are only talking about one spacer on one side for the purposes of tipping.

So what would the 1.25" spacers on either side add?

Add to what? Tip angle? Track inches? Inverse to wallet weight in grams?

 

[RavenTai]

Raven,

I have posted comments in the past pointing out how wider tires, spacers and such do not materially reduce tipover danger (in fact under most conditions wider tires INCREASE tipover danger). But I was literally giggling when I finished your post as I did similar analysis and posted it on another thread years ago, and yours made me laugh at how precise you were.

Suffice to say that I believe you are correct and it's an overall negative to do. Thanks for the analysis and time.

DougM (still giggling)

Thanks Doug.

But I am interested in hearing how wider tires could increase tip over hazard? I would think they would make a slight improvement or no meaningful change. Not sure where the negative comes from?

 

[Gold Finger]

Of course the best way to increase the angle before tip over takes place is to have a heavier wheel tyre combination, this is what some agro tractors adopt, they bolt on weights which are quite substantial which not only prevents nose up when drafting but when on all four wheels makes a significant difference in tip angl, I can get them for my Alpine Tractor but considering they are only cast iron they are very expensive.

 

[RavenTai]

yep heavier wheels/tires lower the CG but not by much for our rubber tires, lift, adding a rack, carrying stuff in the rack all raise the CG.

anybody know what the tip over angle of a stock 80 is? with that the info the actual height of the CG could be calculated.

if anybody is interested tonight I can try to dig up my weight and ballace notes, with that we can figure up almost exactly what changes like lift, racks, tires, sliders, bumpers ect do to tip over angle.

all you need to know is how much the object weights and how far above or below the GC it is installed.

 

[T Y L E R]

This is quickly deteriorating into chat !


TY - dunce cap on .. seated in corner; confus-sed

 

[IdahoDoug]

Gold,

Adding mass to the opposite side is definitely not the best way to prevent rollover. It's one way, but is about as resource wasteful as possible.

Raven,

I'll try to find a post I put together on this whole tipover thing and post it. The gist of it is that if you're at the limit of rollover while cornering you'd really really love the truck's outboard tires to slide and bail you out. The stock tires and width were tested to provide a reasonable envelope of safety and will slide (show of hands who's actually slid their 80 on dry pavement?) even when the larger downforce of extreme cornering is making the outboard tires grip better (but not enough to "trip" the truck and make it roll). Toss wider tires in and the increase in grip as the higher downforce occurs may well be enough to roll the truck on dry pavement.

DougM

 

[T Y L E R]

*raising hand*

I am comfortable sliding out thru 90 degree turns on dirt at 80 kmh. Two yrs ago I passed a slower moving vehicle. Problem was I wanted to make a right hand turn just up ahead. I hammered it, and when I realized I hadn't left myself enough time to slow and turn, I just cranked the wheel to avoid being rear ended. The 2.5" lifted 80 on 315's slid thru that turn like a pro, and I could smell burning rubber immediately. Definately feels wierd sliding out in a turn in a tank...


Now I have to consider this new info in my decision to move into 16x10's this summer. Should be fine as long as I drive accordingly ...


TY

 

[IdahoDoug]

My hand's up too. Los Angeles 405 southbound exit onto Bolsa Chica into Huntington Beach. Rippin that exit curve in excess of 72 and you're drifting. Lord help ya, if your tires are not at proper pressure. Heh - memories.

DougM

 

[RavenTai]

Raven,

I'll try to find a post I put together on this whole tipover thing and post it. The gist of it is that if you're at the limit of rollover while cornering you'd really really love the truck's outboard tires to slide and bail you out. The stock tires and width were tested to provide a reasonable envelope of safety and will slide (show of hands who's actually slid their 80 on dry pavement?) even when the larger downforce of extreme cornering is making the outboard tires grip better (but not enough to "trip" the truck and make it roll). Toss wider tires in and the increase in grip as the higher downforce occurs may well be enough to roll the truck on dry pavement.

DougM

No need I see where you are going with that, high speed cornering like an avoidance maneuver or unexpected twist in the road, I was thinking off road crossing a steep hill sideways at 2 MPH,

 

[IdahoDoug]

Exactly - you got it. And several had claimed "my rig handles so much better with wider tires" which I pointed out was fallacy and placebo effect. You're not getting any better handling/grip from wider tires until you're in the incipient slide (dangerous) zone, which is precisely when you want the tires to act as a fuse to help you, rather than to grip more and roll you. blah blah.

DougM

 

[dclee]

I'll try to find a post I put together on this whole tipover thing and post it. The gist of it is that if you're at the limit of rollover while cornering you'd really really love the truck's outboard tires to slide and bail you out. The stock tires and width were

Doug -

I think first we need to clarify the context of "tip-over." For many, especially those who drive primarily on sealed roads, what you say is exactly correct. In fact, there is another danger if you "over-tire" for a set wheel width, which is rolling the tire right off the rim, which, of course, could be quite unpleasant at speed.

But the other context, which is where my perspective is for this particular truck (since I don't daily-drive it and it mainly gets used off the pavement), is low speed trail stability. In that case, wider tends to be better. Not only for stability, but also for low-pressure grip on rocks and other similar surfaces.

My $0.02,

 

[IdahoDoug]

Derek,

The same principles apply generally. Not always, not with the same precision and the variables of offroad surfaces preclude measurement, but a slide is still preferable to a roll. Can't speak for the low pressure grip on rocks, either as again I've never seen anyone try to measure this highly variable and random surface. However, there's plenty of data that show the elongated tire contact patch of a narrower tire provides more pulling grip than the wider and shorter contact patch of a wide tire on pavement. Logic dictates this would also apply on irregular rock, but no data.

DougM