towing capacity

[forester2008]

we have a class C with a Ford 450 engine. The towing capacity is stated at 5000 lbs. We have a car hauler which weighs 1300 lbs and a vehicle that weighs 3900 lbs which puts us about 200 lbs over the recommended amount to be towed. How risky is it to go 200 lbs over the towing capacity?

[TXiceman]

Using a car hauler trailer you need to be concerned with how much the tongue of the loaded trailer weighs. The larger class C's are often limited on GAWR for the rear axle. A couple of hundred pounds on GCWR is not a real problem, but excess weight on the rear axle can over load the rear suspension and the tire rating. Loading the rear axle excessively can cause the front to go light and cause steering problems. So proceed with caution.

Also, welcome to iRV2.

Ken

[forester2008]

I appreciate your reply, Ken...My wife and I have a lot to learn as new RVers...and all these acronyms.

Matt C.

[forester2008]

How does one measure tongue weight?

[Rick 2005 Dolphin 5376]

Tongue weight is the weight that your trailer induces on your hitch of the motor home. Most gas fired RV's have a 500lbs limit. You can weigh it statically or weigh your RV first with out it, then add it and weigh it again hooked up. A 4 down toad will not add tongue weight. A trailer or tow dolly will

[forester2008]

Thanks, Rick...Now how can I calculate the tongue weight?

[TXiceman]

The only real way to find the tongue weight is by weighing the trailer tongue with the car on the trailer. Typically you need a minimum of 10% of the trailer total weight on the tongue. So as an estimate, you will have a minimum of 520# on the tongue or hitch. This weight is pressing down back past the rear bumper and will add some weight to the rear axle and like a see-saw make the front axle be lighter.

You need to weigh the class C loaded for a normal trip. The water tank on most class C's is in the rear or behind the rear axle. Plan to never travel very far with the tank full. water weighs 8.33 #/gallon so the weight ads up fast.

The terms are:
GVWR Gross Vehicle Weight Rating- The most weight the vehicle can support on it's two axles.
GCWR Gross Combined Weight Rating - The most the RV plus the towed load can weigh.
GAWR Gross Axle Weight Rating. - The most weight you can put on an axle.

These are manufacturers ratings are for the vehicle and there a no laws to prevent an individual from over loading, other than common sense. Truck drivers with commercial rigs have weight ratings that they have to follow.

We had a 1999 Class C with the E450 chassis and it was 31' long with no slide outs. Just the motorhome with 1/4 tank of fresh water, empty waste tanks, normal camping supplies, me and the wife, our total weight was 13,950#. The GVWR was 14,050#...100# to spare. We were pretty close on rear GAWR and had about 75# to spare on the front axle. We towed a 3000# car 4-down.

The larger class C's don't leave a lot of room on capacity, so watch your numbers and do weigh the RV as a starting point.

Ken

[Rick 2005 Dolphin 5376]

Quote:

Originally Posted by TXiceman The only real way to find the tongue weight is by weighing the trailer tongue with the car on the trailer. Typically you need a minimum of 10% of the trailer total weight on the tongue. So as an estimate, you will have a minimum of 520# on the tongue or hitch. This weight is pressing down back past the rear bumper and will add some weight to the rear axle and like a see-saw make the front axle be lighter. You need to weigh the class C loaded for a normal trip. The water tank on most class C's is in the rear or behind the rear axle. Plan to never travel very far with the tank full. water weighs 8.33 #/gallon so the weight ads up fast. The terms are: GVWR Gross Vehicle Weight Rating- The most weight the vehicle can support on it's two axles. GCWR Gross Combined Weight Rating - The most the RV plus the towed load can weigh. GAWR Gross Axle Weight Rating. - The most weight you can put on an axle. These are manufacturers ratings are for the vehicle and there a no laws to prevent an individual from over loading, other than common sense. Truck drivers with commercial rigs have weight ratings that they have to follow. We had a 1999 Class C with the E450 chassis and it was 31' long with no slide outs. Just the motorhome with 1/4 tank of fresh water, empty waste tanks, normal camping supplies, me and the wife, our total weight was 13,950#. The GVWR was 14,050#...100# to spare. We were pretty close on rear GAWR and had about 75# to spare on the front axle. We towed a 3000# car 4-down. The larger class C's don't leave a lot of room on capacity, so watch your numbers and do weigh the RV as a starting point. Ken

Good write up!

[forester2008]

Ken, excellent input, your response is much appreciated..So I guess the bottom line is this...the tongue weight that is necessary for the load I'd be towing (520lbs) is too much for our rear axle and rear tires to handle. I see that our RV limitations for tongue weight is 500 lbs. I would not want to risk going over that.

If anyone knows of someone interested in an all aluminum hauler that is unused, they can contact us. I've now learned that if and when we tow a vehicle it will have to be 4 down....but I realize that there are limited cars that can be towed.

if anyone has recommendations as to a year, make and model for a towable car, let me know

Matt

[TXiceman]

You see many pulling weight way beyond the capacity of the class C chassis. I am not saying you can't, but point out where you will be which is probably over the ratings for the chassis and the problems you may encounter.

How big is your C? The larger ones also have a tendency to what is referred to as Bump Steer or Roll Steer. As you roll down the highway, the coach has a tendency to roll from side to side which requires a constant see-saw steering correction. The cure for this is id large heavy duty anti-roll barswith urethane bushings and Bilstein shock absorbers on the front and rear. The anti-roll bars supplied by Ford are not up to the job of controlling the side to side roll of the large box added to the chassis.

They also have a tendency to have the engine cover and front floor get very hot when driving in warm and hot weather. I added a 3/8" thick foil backed fiber high temp insulation under the carpet and the back side of the engine cover. The best insulation to use is from J.C. Whitney, not the foil backed bubble stuff from the home improvement centers or Camping world.

Ken

[forester2008]

it is a 31 ft. class C, Ford V10, "triton" engine, 305 horsepower, 6.8 liter.

[Romeo]

How does one measure tongue weight?

Forester2008...

I didnt see where they answered your question, so I will according to what I have been told and if wrong, someone can correct me.

I have been told that one can measure tongue weight with any scale that will register enough weight (bathroom scales) by placing it under the tongue or tongue jack. You would need to have the trailer loaded with the intended load, of course.

[TXiceman]

The easiest way to measure tongue weight is to use a house scale and a fulcrum and multiply th scale reading by the fulcrum leverage factor. I am on my net book on a slow WiFi this weekend and will have to follow up next week. Hopefully, another engineer can get on ans provide you a sketch of the procedure.

Ken

[forester2008]

I appreciate everyone's input on this issue...I learned a great deal.