Tahoe vs Suburban

wnjj wrote:

JBarca wrote:
Hi Guys,

I used to have a 2002 K1500 Tahoe and replaced it with a 2003 K2500 Suburban. Both where good trucks, the Burb even had rear wheel steering (Quadrasteer). I sure miss that truck, we just grew out of the towing capacity. I have measured both and here is the differences concerning wheel base and rear overhang.

If I put my Reese HP WD shank in the truck receiver I had this:

2002 K1500 Tahoe:
- 116" wheelbase
- 58" rear overhang (rear axle to tow ball)

2003 K2500 Suburban:
- 130" wheelbase
- 65" rear overhang

One would think the shorter rear overhang would give the Tahoe an advantage, however the math says no.

A rule of thumb for towing stability is the rear overhang is no more than 1/2 the wheelbase. So lets see.

Tahoe: 116/58 = 2 Or the rear overhang is exactly half the WB

Suburban: 130/65 = 2 Or the rear overhang is exactly half the WB

so the ratio of rear overhang to WB is the same.

Now lets look at the force moments if we apply a 500# side load agasint the tow ball. What is the force of resistance at the front axle?

(Summating forces around the rear axle)

Tahoe: 500# x 58" = Y# x 116" Solving for Y, 250# seen at the front axle.

Suburban: 500# x 65" = Y# x 130" Solving for Y, 250# seen at the front axle.

According to the math, as far as WB and rear overhang there is no difference in stability between the Hoe and the Burb.

If the Burb with 130" WB had a 58" rear overhang, it would be better.

From what I have found, tire sidewalls flex will have a significant effect on towing stability, even in the 2500 Burb. Been there and felt/proved that. The wrong tires, LT E load range or not can make or break the stability of a tow rig. It was more of a factor then the rear overhang concern in this case.

Hope this helps

John

I completely agree with your data and calculations, well done, I respectfully disagree with your conclusion of them having the same stability. When the front tires sees those 250 lbs of side load, the sidewalls act a bit like springs and deflect. Given that both vehicles deflect the same amount sideways at both the front and rear wheels, the longer wheelbase one will be traveling closer to its original course than the shorter one. That is more stable in my book. I calculated over a 14% difference in angle of travel between the two using 1/2" of lateral movement at rear and 1" at the front. ( angle = arctan(1.5 / wheelbase) ). For a simple demonstration, set a ruler and a yardstick down and then move one end of each of them sideways by an inch. That smaller one will be pointing more sideways. While the difference is more subtle with the vehicles, it's still real.

This sideways yaw angle is one of the things that stiffer sidewalls help to minimize, regardless of the vehicle.

Hi wnjj,

H'mm good point. I did not think of that. Thank you for pointing that out. I was more after the leverage effect and missed the displacement at the front axle.

Now seeing this, I agree with you. If the rear overhang to WB ratio is the same, then the longer WB does have an advantage due to the displacement at the front axle will be less due to less angle. This will even be higher stability if the longer wheelbase, shorter rear overhang is in your favor.

While I can see the less angle being better, how much angle less it takes to gain a notable level of higher stability is another good question. It is for sure part of the equation.

When we bought our smaller camper we had the Tahoe. After becoming more educated I realized the rear axle in the 1500 was going to be in trouble when I fully loaded the camper and even before I reached that point. I still remember the feeling in the 2500 Burb the day I put the camper on the back of the truck and drove down the driveway. There was a global shift in left to right stability in the truck from the increased capacity of the 2500 rear suspension. You can fell it being more solid and less truck roll even at 10mph.

Then we bought our bigger camper we have now and we used the 2500 Burb on this camper now again only partly loaded it until I reached a 1,200# tongue weight and what gear I could in the camper until I came almost on top of the CGWR of the Burb. 15,750# GCW to a 16,000# GCWR. We used it this way for about 4 months until the F350 came.

Then the same thing, the day I put this camper on the back of the F350 driving down the same driveway, I felt that same global shift in stability. The F350 is 156.7" WB compared to the 130" of the Burb and both with 65" rear overhang however the truck suspension plays a role in rig stability too. Out on the open road at speed, then the longer wheel base helps combined with the more stable truck suspension.

When a wind gust hits the side of the camper, that force pushes on the towball and it pushes/starts to roll the truck suspension and the tires.

- Tire side wall stiffness
- TV WB
- TV rear overhang
- TV suspension/capacity stiffness
- TT length
- TT TW per GVW
- TT running gear/suspension

All of those factors are parts of the towing stability equation. Best is to get "all" of them as optimal as you can.

Thanks again

John