Here is an Auto Show inspired wish list for the “perfect” tow vehicle…
By Andy Thomson
If there is one question we get more than any other it’s the one above. “Is this vehicle big enough to tow that trailer?”
To answer it we generally go into a long explanation about suspensions, centre of gravity, tire sizes and so on. However I have been thinking that there might be a better approach to the tow vehicle question.
No one ever asks if a Suburban is too small for towing and they are a popular tow vehicle. What I have done, with apologies to Chevrolet, is use the magic of Photoshop to transform a Suburban into an even better tow vehicle than it already is.
Here’s how I would transform the classic tow vehicle:
Step 1: Reduce the rear overhang by 19”. Reducing rear overhang even a few inches improves stability substantially so 19” is a massive improvement.
The wheelbase remains 130” just the overhang is less. This reduces the percentage of overhang from 43% to 28% of the wheelbase.
Step 2: Improve the tire size. Most SUV’s and trucks come with large soft tires that can usually be reduced in size to improve handling. Since we have now reduced the weight of the Suburban we can change to a narrower lower profile tire with ¼ of the sidewall roll.
Step 3: Since the tire is smaller it can travel further into the wheel wells without rubbing so we can now lower the Suburban. A lower vehicle has a lower centre of gravity for more handling stability and reduced drag.
Step 4: The obstacle to lowering the Suburban is the back axle would be too close to the frame limiting suspension travel. Since we can wish for anything we want we will just change to independent rear suspension. Now there won’t be a conventional axle to get under the frame. While we are at it we could also change to a unit body construction for a more ridged structure and some weight savings.
With independent suspension we widen the rear suspension stance from 42” to 67”.
Independent suspension has a fraction of the un-sprung weight. This combined with the wider stance gives a smoother ride along with the improved handling.
Another way to look at what we have done is to pretend we are looking at the two vehicles from below. The red dots are the ball location and the points of the suspension stance. Here you can see how much less leverage the ball has on the rear suspension.
Step 5: Since we have taken away the space for the third seat we can lower and lengthen the first two rows of seats. This allows us to lower the body and the roofline. This lowers the centre of gravity even more. It also would improve aerodynamics for better mileage and more performance.
So in the end we have a Suburban that is in every respect a much better handling and performing tow vehicle that gets better fuel economy. However it looks much smaller, even though it is not actually smaller in any of the dimensions that count – such as the wheelbase or track, and the rear suspension stance is actually larger. So you see size is not all that matters in a tow vehicle.
Just like the real automotive engineers, we have had to make some compromises. For example, the third seat is gone, and we would require run flat tires as there is nowhere to put a spare. As a solo vehicle, the back tires might be a little light for good snow traction but you could solve that by changing it to a front wheel drive which has some traction and durability advantages.
Would GM build this ultimate tow vehicle? It is hard to say if there is enough market to justify the investment. After all, GM does make a shorter version of the Suburban – the Tahoe or Yukon on a 116” wheelbase. Why not just keep the longer wheelbase on these vehicles? The answer is that everything has its tradeoffs. A longer wheelbase Tahoe would not maneuver any easier than a Suburban, and then there is that spare tire problem again. The vast majority of people purchasing a Tahoe are not looking for the last word in towing so it would not likely sell nearly as well as the existing design.
So one might be tempted to ask the question – which vehicle is closest to our modified Suburban?
The closest SUV I can think of is GM’s Buick Enclave, Chevrolet Traverse or GMC Acadia. This trio of mid-size sport utes does not have the super low overhang percentage but at 39% it is better than many. It does have the low centre of gravity, all wheel drive, 19” rims with pretty good tires, independent rear suspension and these are outstanding tow vehicles from a handling perspective.
I hear through the grapevine that the next generation Suburban is going to be built on the Enclave platform. Perhaps the engineers will lengthen the wheelbase a little, and reduce the rear overhang, and just maybe we will have our dream Suburban tow vehicle after all!