Originally Posted by tdf-texas
I am buying a 21' and will be towing with a Tundra Crewmax 4x4. That puts the truck weight at more than 2000 lbs more than the loaded weight of the trailer. Towing capacity is over twice the trailer weight.
Currently, I do not think I need a WDH - am I wrong?
What does Toyota say? They know the vehicle better than we do. I don't know what year of truck this is, but the 2015 Tundra owner's manual says:
If the gross trailer weight is over 5000 lb. (2268 kg), a weight distributing hitch with sufficient capacity is required.
I note that Toyota always (for all models of Toyota, for all conventional trailer) directs the user to have 9% to 11% of the trailer's gross weight on the tongue, so there is an assumption built in that 5,000 pounds of trailer means 450 to 550 pounds of tongue weight. So, no, it is not required, but you could get close to the point at which your tongue weight hits the same level as a trailer for which Toyota says to use a WDH (which looks like 550 pounds or 250 kg to me).
The relationship between towing capacity (which is based mostly on the engine and transmission) and the weight of the trailer doesn't give you any indication of whether you need a WDH, or whether it would be beneficial. The highest towing capacity for a Tundra is almost double the lowest capacity, for the same wheelbase; two Tundras of the same wheelbase would have the same need (or lack of) for a WDH, so the rated capacity means nothing to the need for WDH.
The truck being substantially heavier than the trailer is very roughly an indication that the truck is unlikely to have problems handling the trailer's weight, but that isn't very helpful in determining whether a WDH is suitable. A WDH doesn't make the trailer any lighter or easier to pull, so this isn't really a question of trailer weight.
The information that you don't
mention is what is
relevant to WDH use:
- The truck has a very long wheelbase, so it is less affected by the hitch weight than a shorter vehicle; a WDH changes the effect of hitch weight on the tow vehicle's axle loads, so the truck's wheelbase length suggests that a WDH would be less useful than with other tow vehicles and the same trailer.
- The truck has substantial rear axle capacity, so adding the entire tongue weight (plus some more due to leverage) to the truck's rear axle and suspension is not likely to be a problem at all. A WDH transfers load from the truck's rear axle and to the truck's front axle and to the trailer axles; since you don't likely need to do that - and it probably wouldn't even be beneficial to do that with a rear-wheel-drive tow vehicle like this - this common (and most fundamental) reason for using WDH doesn't likely apply.
Many people seem to use weight-distributing hitches not for their fundamental purpose (shifting load between axles) but for the side effects: restraining motion between the tow vehicle and trailer. Even with the Tundra, as others have mentioned, you may prefer the ride with WDH.