Cheers everyone. We are soon-to-be first time RVers who have just spent time diving into the research on towing requirements for trucks and fifth wheels. We just bought our truck - an F350 DRW - and are aiming to buy a fifth wheel in the spring. I thought it might be helpful to summarize a few of the things we've learned recently in case it can help others.
A couple of caveats. We have not applied these rules in practice yet, so this is just me conveying information based on research we've done, not experiences we've had. In addition, I may not be using exactly the right weight terms in each instance here. On either front, I'm happy to have any long-timers correct me.
That said, here's what we've learned:
First, very few RV or truck salespeople truly understand weight and towing figures. If they do, they don't share. When talking to them, keep in mind that their job is to make a sale. Our conclusion is that most of the ones we've met are honest, but they don't really know their stuff. They know the basics, but when you start getting into the weeds you won't get specific answers. It also appears fairly common that RVers push or exceed the limits on their towing capacity and get away with it, leading many dealers to tell you that "people do it all the time." One salesman told us that we could easily tow a GD 2930 Solitude with an F350 SRW, saying that if it were him he would "do it all day long," but when we ran the numbers we realized that with a sliding hitch, two passengers and two dogs, we would be at 105% of the maximum truck payload weight, even without any bags or guests in the truck. In light of that, you can't really rely on what you are being told. You must do your own research.
Second, doing your own research doesn't mean you'll get clear answers. You'll get a wide range of answers and opinions, oftentimes totally contradictory. This is a situation where you need to get all the information, then make your own decision. As Lee Iacocca once said, "think for yourself." That is necessarily going to include making your own risk assessment of what kinds of safety margins you prefer.
Third, before diving into the requirements on particular trucks and fifth wheels, learn about the 80/20 rule. This is a safety rule of thumb which basically says that you should not exceed 80% of the various weight limits on your towing vehicle. Many dealers will tell you that you don't need to apply the rule, that many people ignore it and tow their fifth wheels just fine, etc. We have found that the best and most helpful posts on the forums posted by experienced RV owners advise that you should follow the rule. There are many reasons why it makes sense: individual vehicles may vary from factory weight ratings, the manner in which you load the vehicles can affect the weight ratios, the driving conditions which you experience may vary from the straight and narrow roads which oftentimes underlie the factory's weight calculations, your two largest friends may want to pile in the truck with you and affect the payload, etc. Based on the best advice we've received, you're going to want a cushion. Doing that not only helps with actual safety, it helps with peace of mind, which is a major reason why we want to go RVing in the first place.
Fourth, when doing your planning don't make the mistake of focusing on just a truck's towing capacity at the expense of hitch weight / pin weight. The towing capacity of many newer 350 or 3500 SRW trucks is quite high. For example, a 2022 F350 SRW may be able to tow 19,000 pounds. Applying the 80/20 rule to that figure, you could safely tow a fifth wheel with a full (i.e., GVWR) weight of 15,200 pounds. But if you don't also pay attention to the payload figure, you may buy a fifth wheel that you can tow but that may make the overall weight of your truck too high when you add other parts of the payload like passengers, dogs, bags, weight of the tow hitch installed in the bed, etc.
So when buying a truck, always look at the payload sticker that is on the truck (ours was on the door jam). For Ford trucks, it says that the maximum weight of passengers and cargo is X pounds. We were told that, in applying this figure, you don't take into account the weight of the fuel in the truck - that is already factored in. They are really talking about the weight of things you put into the fully-fueled truck, including passengers, dogs, bags, the weight of the hitch, anything else you put in the bed, etc. When deciding on a fifth wheel, the basic formula that you need to do is to take the payload figure on the sticker (for example 3,400 pounds), subtract the likely weight of passengers and cargo that you put in the truck (for example 1,000 pounds), and then the remaining number gives you the weight that the truck can safely handle from the weight of the fifth wheel sitting on your hitch in the bed of the truck (in this case, 2,400 pounds). There are other weights such as axle rating that you also need to review, but it seems to us that those numbers are pretty safely met if you are within the limits on towing capacity and hitch weight.
Fifth, when doing the calculation of hitch weight from the fifth wheel, you will get widely varying figures on what percentage of the fifth wheel's weight will be transferred to the truck. The typical ratios that we saw ran from 15-25%. It appears that, in recent years, the percentage has dropped as fifth wheel manufacturers have revised their manufacturing. For most Solitudes, it looked like the dry weight ratio (i.e., as the empty vehicle comes out of the factory) is roughly 20%. But the percentage that is actually achieved in any given circumstance, which depends on what you put in the fifth wheel and where you put it, makes a huge difference. For example, if you have a fifth wheel weighing 15,000 pounds fully loaded, if you load it in such a manner that the weight ratio going to the truck is 15%, then 2,250 pounds is being placed on the bed of your truck. If, however, you load it so that the ratio is 25%, 3,750 pounds is being applied. That may not make a huge difference if you have a dually / DRW truck, which oftentimes have payload capacities in the 5,500 range, but it can make a huge difference if you have a SRW. Even at 15% you may be close to or exceeding the payload capacity of a SRW truck. If you load the fifth wheel in such a manner that you are at 25%, you will likely be way over the limit.
When buying a truck and a fifth wheel, you also have to recognize that you cannot accurately know in advance what ratio would be applied until you actually get out there and start using your fifth wheel. Before you buy it, you're not allowed to take the fifth wheel off the dealer's lot to go to a weighing station and test it with your truck. So you have to plan ahead. The most helpful posts that we saw from RV owners said to make sure that your towing vehicle could handle the weight of a fully loaded fifth wheel with a 25% weight ratio on the hitch. That's obviously a conservative approach, but we decided that it made sense for us, and hence we've gone with a dually rather than an SRW in order to be able to tow fifth wheels the size of a Solitude.
Sixth, there is virtually no information out there on the question of whether you should apply the 80/20 rule to the truck's payload weight in addition to towing capacity. Most dealers told us that no one had ever asked the question, or that the 80/20 rule only applies to towing capacity but not hitch weight. There does not appear to be a clear answer. Since the 80/20 rule is just a common sense rule of thumb to increase your safety margin, we've decided to apply it to hitch weight as well as towing capacity. We don't want to be towing our fully loaded fifth wheel up the Rocky Mountains in high winds with friends or family in the back seat and then find out we should have been more conservative.
Seventh, when buying a fifth wheel make sure that you don't rely just on the factory ratings for things like UVW (unloaded vehicle weight); look at the sticker that actually appears on that particular vehicle. When looking at one fifth wheel, we found that the dry weight for that particular unit was a few hundred pounds over what was on the Grand Design website as the standard UVW. You need to look at the number that applies to your particular unit when starting your calculations.
Eighth, there are lots of posts out there from RVers who said that they made the mistake of trying to drive a large fifth wheel with an SRW, only to realize after the fact that they needed a DRW. We've taken that to hear.
That summarizes what we've learned so far. As noted above, since we're new to this take these comments with a grain of salt.
We're looking forward to meeting some of you when we get out on the road!
A couple of caveats. We have not applied these rules in practice yet, so this is just me conveying information based on research we've done, not experiences we've had. In addition, I may not be using exactly the right weight terms in each instance here. On either front, I'm happy to have any long-timers correct me.
That said, here's what we've learned:
First, very few RV or truck salespeople truly understand weight and towing figures. If they do, they don't share. When talking to them, keep in mind that their job is to make a sale. Our conclusion is that most of the ones we've met are honest, but they don't really know their stuff. They know the basics, but when you start getting into the weeds you won't get specific answers. It also appears fairly common that RVers push or exceed the limits on their towing capacity and get away with it, leading many dealers to tell you that "people do it all the time." One salesman told us that we could easily tow a GD 2930 Solitude with an F350 SRW, saying that if it were him he would "do it all day long," but when we ran the numbers we realized that with a sliding hitch, two passengers and two dogs, we would be at 105% of the maximum truck payload weight, even without any bags or guests in the truck. In light of that, you can't really rely on what you are being told. You must do your own research.
Second, doing your own research doesn't mean you'll get clear answers. You'll get a wide range of answers and opinions, oftentimes totally contradictory. This is a situation where you need to get all the information, then make your own decision. As Lee Iacocca once said, "think for yourself." That is necessarily going to include making your own risk assessment of what kinds of safety margins you prefer.
Third, before diving into the requirements on particular trucks and fifth wheels, learn about the 80/20 rule. This is a safety rule of thumb which basically says that you should not exceed 80% of the various weight limits on your towing vehicle. Many dealers will tell you that you don't need to apply the rule, that many people ignore it and tow their fifth wheels just fine, etc. We have found that the best and most helpful posts on the forums posted by experienced RV owners advise that you should follow the rule. There are many reasons why it makes sense: individual vehicles may vary from factory weight ratings, the manner in which you load the vehicles can affect the weight ratios, the driving conditions which you experience may vary from the straight and narrow roads which oftentimes underlie the factory's weight calculations, your two largest friends may want to pile in the truck with you and affect the payload, etc. Based on the best advice we've received, you're going to want a cushion. Doing that not only helps with actual safety, it helps with peace of mind, which is a major reason why we want to go RVing in the first place.
Fourth, when doing your planning don't make the mistake of focusing on just a truck's towing capacity at the expense of hitch weight / pin weight. The towing capacity of many newer 350 or 3500 SRW trucks is quite high. For example, a 2022 F350 SRW may be able to tow 19,000 pounds. Applying the 80/20 rule to that figure, you could safely tow a fifth wheel with a full (i.e., GVWR) weight of 15,200 pounds. But if you don't also pay attention to the payload figure, you may buy a fifth wheel that you can tow but that may make the overall weight of your truck too high when you add other parts of the payload like passengers, dogs, bags, weight of the tow hitch installed in the bed, etc.
So when buying a truck, always look at the payload sticker that is on the truck (ours was on the door jam). For Ford trucks, it says that the maximum weight of passengers and cargo is X pounds. We were told that, in applying this figure, you don't take into account the weight of the fuel in the truck - that is already factored in. They are really talking about the weight of things you put into the fully-fueled truck, including passengers, dogs, bags, the weight of the hitch, anything else you put in the bed, etc. When deciding on a fifth wheel, the basic formula that you need to do is to take the payload figure on the sticker (for example 3,400 pounds), subtract the likely weight of passengers and cargo that you put in the truck (for example 1,000 pounds), and then the remaining number gives you the weight that the truck can safely handle from the weight of the fifth wheel sitting on your hitch in the bed of the truck (in this case, 2,400 pounds). There are other weights such as axle rating that you also need to review, but it seems to us that those numbers are pretty safely met if you are within the limits on towing capacity and hitch weight.
Fifth, when doing the calculation of hitch weight from the fifth wheel, you will get widely varying figures on what percentage of the fifth wheel's weight will be transferred to the truck. The typical ratios that we saw ran from 15-25%. It appears that, in recent years, the percentage has dropped as fifth wheel manufacturers have revised their manufacturing. For most Solitudes, it looked like the dry weight ratio (i.e., as the empty vehicle comes out of the factory) is roughly 20%. But the percentage that is actually achieved in any given circumstance, which depends on what you put in the fifth wheel and where you put it, makes a huge difference. For example, if you have a fifth wheel weighing 15,000 pounds fully loaded, if you load it in such a manner that the weight ratio going to the truck is 15%, then 2,250 pounds is being placed on the bed of your truck. If, however, you load it so that the ratio is 25%, 3,750 pounds is being applied. That may not make a huge difference if you have a dually / DRW truck, which oftentimes have payload capacities in the 5,500 range, but it can make a huge difference if you have a SRW. Even at 15% you may be close to or exceeding the payload capacity of a SRW truck. If you load the fifth wheel in such a manner that you are at 25%, you will likely be way over the limit.
When buying a truck and a fifth wheel, you also have to recognize that you cannot accurately know in advance what ratio would be applied until you actually get out there and start using your fifth wheel. Before you buy it, you're not allowed to take the fifth wheel off the dealer's lot to go to a weighing station and test it with your truck. So you have to plan ahead. The most helpful posts that we saw from RV owners said to make sure that your towing vehicle could handle the weight of a fully loaded fifth wheel with a 25% weight ratio on the hitch. That's obviously a conservative approach, but we decided that it made sense for us, and hence we've gone with a dually rather than an SRW in order to be able to tow fifth wheels the size of a Solitude.
Sixth, there is virtually no information out there on the question of whether you should apply the 80/20 rule to the truck's payload weight in addition to towing capacity. Most dealers told us that no one had ever asked the question, or that the 80/20 rule only applies to towing capacity but not hitch weight. There does not appear to be a clear answer. Since the 80/20 rule is just a common sense rule of thumb to increase your safety margin, we've decided to apply it to hitch weight as well as towing capacity. We don't want to be towing our fully loaded fifth wheel up the Rocky Mountains in high winds with friends or family in the back seat and then find out we should have been more conservative.
Seventh, when buying a fifth wheel make sure that you don't rely just on the factory ratings for things like UVW (unloaded vehicle weight); look at the sticker that actually appears on that particular vehicle. When looking at one fifth wheel, we found that the dry weight for that particular unit was a few hundred pounds over what was on the Grand Design website as the standard UVW. You need to look at the number that applies to your particular unit when starting your calculations.
Eighth, there are lots of posts out there from RVers who said that they made the mistake of trying to drive a large fifth wheel with an SRW, only to realize after the fact that they needed a DRW. We've taken that to hear.
That summarizes what we've learned so far. As noted above, since we're new to this take these comments with a grain of salt.
We're looking forward to meeting some of you when we get out on the road!