Why Are Lightweight Vehicles Better Off-Road Than Heavier Vehicles, Or Are They?

[Rodeoflyer]

so what about 6 wheels, or 8 wheels?

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[DadJokes]

Or lower weight and have less resistance to movement/acceleration thus needing less tire and get away with a little harder compound too I’d think = more tire life.

 

[sardog12]

True, but I mean because moving more mass requires the application of more torque then wouldn't the extra pressure from the extra weight pushing down harder on the tires provide that extra grip in order to get traction?
Also, if you widen and enlarge the tires to a certain degree then you'll basically distribute the weight of the vehicle and as such shouldn't the extra torque applied to move the vehicle also be distributed? This would, in turn, be exactly the same as a much lighter vehicle, no?

Stop trying to overthink this. A lighter vehicle requires less effort to make it move, is more nimble, has less wear on parts, and has better handling characteristics. The traction advantage that you seem to be concerned about can easily be achieved by reducing the tire pressure and increasing the contact patch. Yes, you can try to reason your way through any desired outcome (still won't make it real, though) but why not trust those who have been doing this for years and have the practical experience to know what they are explaining to you? They are not making their points up.

 

[Headbarcode]

This makes perfect sense actually. I've asked five mechanics and two engineers this past week for this answer and none of them could give it to me. Thanks Headbarcode!
So in theory to get over this problem I could increase tire size and width in order to spread out the lb/inch² of the torque that I applied to get the vehicle up the hill and this way the wheel won't slip?

Glad I could help.

For the sake of keeping this simple, let's assume we have 2 different vehicles. One weighs twice as much as the other. Each is, in itself, perfectly proportioned in torque and traction tuned to its physical weight.

Now, put them both in an off road scenario. Inclines far exceeding anything found on any roadway and loose/brittle/unstable ground being traversed.

More physical weight requires more force to get it moving. That force is being directed at that imperfect and unprepped ground.

Put all that together and we can expect that as a vehicle gets heavier and heavier, it's ability to out drive the surface will increase.

 

[Rodeoflyer]

I still like watching these guys.

 

[Humvee4us]

Glad I could help.

For the sake of keeping this simple, let's assume we have 2 different vehicles. One weighs twice as much as the other. Each is, in itself, perfectly proportioned in torque and traction tuned to its physical weight.

Now, put them both in an off road scenario. Inclines far exceeding anything found on any roadway and loose/brittle/unstable ground being traversed.

More physical weight requires more force to get it moving. That force is being directed at that imperfect and unprepped ground.

Put all that together and we can expect that as a vehicle gets heavier and heavier, it's ability to out drive the surface will increase.

This would explain a lot and makes perfect sense. I could, in theory, increase tire size and width until I get the nominal ground pressure proportioned to that of a much lighter vehicle.

However, in order for this to work all four tires would need to have good traction which, as you mention, will not be happening on any uneven/loose off-road terrain. As such, what I used to match my heavier vehicle to a lighter one, dispersing the nominal ground pressure with the tires, has just been completely thrown out of balance if one of the tires is not getting enough contact or loses complete contact with the ground.

Furthermore, if going up an incline and one of the rear tires loses contact with the ground then the vehicle's weight will shift to only three tires and because of the much heavier weight of the vehicle, despite it initially being proportioned in nominal ground pressure to a lighter vehicle, it has now lost that balance and has a higher nominal ground pressure which will, in turn, cause the remaining tires to outdrive the surface.

A lighter vehicle, on the other hand, even if one of its rear tires also loses complete contact with the ground as in the heavier vehicle scenario and as a result the nominal ground pressure also increases, because I'm not relying on the tires as much to disperse the weight of the vehicle because the vehicle is light in weight, I'll still end up with a significantly lower nominal ground pressure giving me a significantly higher probability that I won't outdrive the surface. Makes complete sense, thanks again Headbarcode!

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