F350 v 450

[MapNerd]

Not a debate about which is better. Just looking for others thoughts on whether or not I should consider the 450 given where I’m headed.

We’ve narrowed down to about 5 different 5th wheels. The heaviest of them has a GVWR of 21,000 and since the others are lighter, I’m using the heaviest for my considerations in terms of selecting a tow vehicle. Currently, we’re looking at a 6.7L Diesel F-350 DRW 4x4 with a 4.10 axle ratio. I’m trying to work out the weights to see how close I am and here’s what I came up with.

It looks to me that the 350 would be working pretty hard to pull this unit fully loaded but I’m thinking that maybe I am overlooking some thing. I used 50% water in grey and black to accommodate for the fact that when I know I’ll have sewer at my destination, I like to do a trip with them half full so that the contents and splash around and hopefully loosen any build up.

Cargo in the truck I’m thinking should be around 600lbs (300lbs for wife and I, 125lbs per kid - they aren’t that big yet but they grow fast, dog, stuff, 5er hitch - might add a toolbox once I see how well the unit clears the bed).

So looking at these numbers, would you move to a 450 or stick with the 350? Why?

 

[Gizmo]

Depending on the floor plan but I think the hitch weight would closer to 4800 to 5400 pounds on 21,000 5er. My 35 foot on the cat scales had 3780 at a total weight of 14,500. I always use 25% of the GVWR of the 5er to give me some margin which would be 5250. I have found this website the easiest to use and has come really close on 5ers. I would drive both the 350 and 450 and pay attention to the turning radius, the 450 will turn a lot sharper than a 450 will.

TowingPlanner - towing capability calculators

 

[MapNerd]

Thanks @Gronk. It’s a front kitchen toy hauler. Bed and bath the the rear. Living room center.

aware that the 450 would give me a better turning radius but it’s 11k more and I only get 3K lbs more towing capacity for that. I haven’t been able to determine if that’s just towing capacity or if there would be any increase in payload capacity on an 450.

i figure practice and experience can overcome the slightly worse turning radius. Also the unloaded ride would probably be a lot stiffer on a 450 with the move to 19.5 commercial tires - also more expensive to maintain but if the 350 isn’t up to the job with power to spare then a 450 it is.

 

[TJ&LadyDi]

From my past 5th wheel towing experience, it is hard to be "over-trucked." The opposite is easy!

You've hit the age-old dilemma of balancing the best tow vehicle option with the best "drive to the grocery store" vehicle option. We pulled a much lighter 5th wheel with a F-350 some years back and never had any issues. With a significantly heavier trailer, I'm not sure I would be as comfortable. I think the F-350 would probably pull the 5th wheel you are interested in, but don't know how well it would perform in the mountains. Good luck with your final decision.

TJ

 

[Kevin D Pem]

many that I know go with a used tractor. they are older and some have a smart car loaded on the truck.

 

[FL-JOE]

Since that would be a triple axle toy hauler are you sure that tongue weight is correct. I have just started my research comparing two and three axle toy haulers and am finding that it greatly lowers the tongue weight when they have the 3rd axle.

As far as added cargo. It is fairly easy to estimate added pounds to the TV (tow vehicle). It has been my experience it is harder to estimate added cargo weight to the fiver. We have just over 3,000 "extra" pounds on board right now with our 43' Newmar DP. With our last 39' fiver we were at around 2,400 pounds of "stuff". This was two people full timing so it could be different that your situation.

 

[MapNerd]

It’s a Riverstone 42FSKG. You are correct that the pin weight according to the specs is lower. The Riverstone specs indicate a pin weight of 3,950lbs, which is 20% of 19,750 - 1,250 less than the GVWR of 21,000.

The triple axle is why I am using 20% of GVWR instead of 25%.

 

[MapNerd]

many that I know go with a used tractor. they are older and some have a smart car loaded on the truck.

When I read this, I immediately thought you meant a farming tractor and thought that’s got to be awful slow. Took me a minute to realize you meant a smaller freightliner truck.

 

[MapNerd]

From my past 5th wheel towing experience, it is hard to be "over-trucked." The opposite is easy!

You've hit the age-old dilemma of balancing the best tow vehicle option with the best "drive to the grocery store" vehicle option. We pulled a much lighter 5th wheel with a F-350 some years back and never had any issues. With a significantly heavier trailer, I'm not sure I would be as comfortable. I think the F-350 would probably pull the 5th wheel you are interested in, but don't know how well it would perform in the mountains. Good luck with your final decision.

TJ

Given that the only place I think I’m close to the line here is pin weight, I’m thinking that it should haul the load just fine. Am I wrong to think that way?

The 21 F350 (the way I’ve configured) is rated to pull up to 34,200lbs. I’d never exceed 80% of that, so that puts my max at 27,360 - still well under the GVWR. Having never towed a 5th wheel, my brain is trying to think about it all logically but I’m second guessing myself wondering if there are unintuitive things about pulling a 5er that I’m not considering.

Being close to the capacity of the rear axle, I’m thinking should just result in maybe a rougher ride? The unit has an air-ride kingpin so that should soften things out as well.

I just don’t see the additional $11K of value in a 21 F450. The only benefits are:

• 3K pounds more haul capacity - no change in bed capacity
• Wide track front end
• 1K lb stiffer springs
• Increased longevity of 19.5” commercial tires (should last 75k-100k miles)

The drawbacks are:

• 11K more to jump up to a 450
• Stiffer ride unloaded as a result of 1k stiffer springs and 19.5” commercial tires
• Increased maintenance costs

Everything else between the two trucks is the same from everything I can tell. It seems at least with the 21’s, 450s are really only worth it for true commercial use or if you’re really pushing the envelope of a 350’s hauling capacity.

With Ford’s ProTrailer Backup Assist, I’m not sure the increased turning radius of a 450 is that big of a deal because its pretty much a turn of a knob and let the truck do the rest.

 

[Joe Hogan]

Here is an interesting discussion on topic