Tow rating with oversize tires

Rselzler · 02-02-2011, 07:05 AM

I have an '06 F-150 with a tow rating of 9100lbs. However, I have added a 3" front coil spacer (level kit) and 2" rear blocks to fit 34.5" tires. I did not change the stock 17" rims. How does this effect my tow ability for a fifth wheel if at all? I seem to get a different answer at each dealer.

BTW- the bed height is now 35" with the mods which I'm thinking shouldn't be a problem since some 3/4 ton trucks have a similar bed height but I did have one dealer tell me I was limited to bumper pull due to bed height.

Please Help!
Ron

**Bama Rambler** · 02-02-2011, 07:38 AM

The down and dirty equation is that you reduced your tow capacity by the same percentage as you increased your tire diameter. So if you went from a 30" tall tire to a 35" tall tire you reduced your tow capacity by 1300 lbs. However, going with taller tires also means that the sidewalls have more flex in them and will make a much poorer towing situation.

If your bed is at 35" then the dealer is correct. That puts your bed rails at near 55" which is too tall for a 5er. You won't find a 5er to match the tow rating of that truck even if it was left stock so it's a mute point.

**Herk7769** · 02-02-2011, 08:24 AM

I know this is not what you wanted to hear; but Bama is correct. Save that truck for your "Party Truck" and buy a different one for towing. Most truck mods REDUCE towing capacity. The stated capacities are with all required options installed. Bigger wheels, mag wheels, etc, reduce the possible load. For example, 4x4 reduces maximum trailer weight by the weight of the extra running gear. The 2 wheel drive equivelent can tow about 700 pounds more trailer similarly equipped.

Rselzler · 02-02-2011, 01:40 PM

Trading trucks or buying a second truck isn't really a good option for me. With the tire size math I have increased 7% in tire size which would reduce my tow rating from 9100 to 8460. I'm looking at a 5th wheel flagstaff with a UVW of 6700# or possibly a Keystone at 7700#. With minimal loading and no additional trailer accessory weight shouldn't I be fine. I'd like to buy a fifth wheel we can grow into as a family. If I am just "ok" with my truck for a couple years I'd certainly go to a F250 next time.

So...... With a lightweight fifth wheel and my current truck can I make do for now? 3 dealers said yes. 1 said no which concerned me. Now 2 of you agreed it won't work. I have a tie at 3 to 3!

The box height issue never came up with any dealers. They said the pin box could be adjusted to accommodate. .???

MtnGuy · 02-02-2011, 01:57 PM

Quote:

Originally Posted by Rselzler

So...... With a lightweight fifth wheel and my current truck can I make do for now? 3 dealers said yes. 1 said no which concerned me. Now 2 of you agreed it won't work. I have a tie at 3 to 3!

I guess I need to break the tie, which is not really a tie, since many dealers are going to tell you anything you want to hear to sell you a trailer. I have a 2006 F150, and no way would I tow a 5th wheel that has a 6700 UVW.

With me sitting in the cab of my truck, TrackRac rails (but not the TracRacs), personal items, and a small tool box in the bed, it weighs right around 6000 lbs. The GVWR on my truck is 7200 lbs. That means that I can load 1200 lbs. more before I reach my GVWR.

The only Flagstaff that I can find that has close to a 6700 lb. dry weight has a 1200 lb. hitch weight......and that is going to only grow as you stock your camper. You will more than likely be over your GVWR even before you add passengers and camping gear to your truck. You are likely to grossly be oveweight going down the road....not a good thing.

LadyWindrider · 02-02-2011, 05:34 PM

Put your truck on level ground. Measure the height to the top of the bed. Now subtract 6 inches, (estimate) for truck sinking when camper weight is applied. Now possible camper sitting level, measure from the bottom of the nose to the ground, (you need the camper level for towing). Now between the camper and the truck height, you need at least 6 inches. So you have some math to do. Camper height level, minus truck height, minus 6 more inches, and the winner is...... If it's a positive number, you might make it oh height. If it is a negative number, forget it, you'll be towing nose high, and you will crunch the side of the bed one day and the camper, and have to fix both. As for weight, you will never be happy towing a 5th wheel. Now you asked for our opinions, and have received, what you do with them is up to you. If you buy a 5th wheel, we may take our opinions back, but the dealer will never take the camper back, EVER!!!!!!! Also the dry weight on those campers don't list Awning, Propane, Battery, etc. Can easily add 500 pounds as you would buy it, so there is another 200 pounds on the pin hitch.

Rselzler · 02-02-2011, 05:39 PM

Thanks all.

**Herk7769** · 02-02-2011, 06:14 PM

windrider covered what i was going to add quite well. The problem with lowering the pin box to clear the bed rails is the camper will no longer sit level when connected. With the increased surface area in the slipstream you will increase drag at highway speeds and most likely destroy the already horrible gas mileage you will get with your overloaded truck.

2-3 mpg could be acceptable to you so i will press on with the other mechanical problems you will encounter. Unless you are pretty level you will have problems with your camper's brakes and axle loading. This is due to the camper's weight not being evenly distributed on the two axles. The rear axle will be carrying a higher percentage of the load than the front axle. This axle loading problem was very thoroughly discussed on a thread about tire failures. This means your brake setting on the controller will be too low for the rear brakes and too high for the front. You might also experience refrigeration issues running it in an "out of level" condition. My vote is still for "de-mod" the truck or tow with something else.

FYI the Ultra-lite 8526RLWS Flagstaff is what I tow with my 2500HD Duramax Diesel. With my spare fuel cans, generator, hitch and wood leveling blocks I max out the truck's gross vehicle weight with the 1400 pound pin I carry. Remember that 15 - 25% of the camper's weight must be on the pin for safe handling characteristics. A 9000 pound when loaded camper like mine has a minimum pin required of 1350 pounds and a maximum of 2250 pounds. The Unladen weight of my camper is 7200 pounds.

Rselzler · 02-02-2011, 07:05 PM

I'm still confused I guess or maybe just I denial that my seams of fifth wheel ownership are being crushed. If I restore factory tires and height I'm looking at a tow rating of 8600# which is one the larger tow ratings for a 1/2 ton truck. The fifth wheel I'm looking at is 7700# so adding a 1,000# of cargo puts me 100# over anyway.

Interesting that these are advertised and even labeled "1/2 ton series"???? Seems to be a joke to advertise that way.

acadianbob · 02-02-2011, 07:41 PM

Quote:

Originally Posted by Rselzler

Interesting that these are advertised and even labeled "1/2 ton series"???? Seems to be a joke to advertise that way.

?? 1/2 ton is 1,000 pounds which refers to load capacity so why is that bad advertising. In fact, most "1/2tons" are rated for significantly more than a 1/2 ton.

Rselzler · 02-02-2011, 08:10 PM

Sorry Acadianbob

It's the fifth wheel, not the truck, that I'm referring to as being a "1/2 ton series" or "1/2 ton towable" but yet most 1/2 ton trucks, it appears, aren't up to the job.

**Herk7769** · 02-02-2011, 08:18 PM

The problem comes in that if you only tow "the camper" and no cargo or family the smaller trucks can do the job. The issue is that no one camps that way. We bring tools, chairs, tables, food, booze, soda, food in cans, steaks and burgers in the freezer, clothes, coats, stereos and CD/DVDs, video games for the kids, bikes and lord knows what else. The biggest complaint is NO STORAGE. We would put in 10,000 pounds of junk in there "Just in case we need it". STILL working on winnowing out stuff we never use. Yet it seems at the last minute I throw it back in anyway. I have never been on a trip yet that the rig weighed less than 9,000 pounds and the truck at 9300 pounds.

In my honest opinion, your 1/2 ton will tow an ultra-lite TT just fine. I saw a Prime Time Travel Trailer at the Phila RV show that has all the room and floor plan of my 8526 and then some. Get a good quality WD hitch with sway control. Make your NEXT truck a 250/2500HD and then when you are ready get a bigger 5th wheel.

lbrjet · 02-02-2011, 08:23 PM

You are right Rselzler, most half tons are not up to the job. It is a marketing gimmic and a lot of people fall for it, then most of them end up with a new truck. They give you a 'dry' pin weight and the actual pin weight will be several hundred lbs. more. Then your payload is exceeded before you load your pickup with stuff and people. Better to learn that now than later.

I also think your 7% math is off a bit.

Rselzler · 02-02-2011, 09:02 PM

Researching some TT's now. I'm glad I found this forum as otherwise I'd surely have believed in the dealers sales pitch because I really wanted to believe. Think I'll go with a TT and save the 5th wheel dream for another day.

Thanks ALL!

**Bama Rambler** · 02-02-2011, 09:14 PM

That's a good idea and even with that you're going to be careful. You've learned one really important lesson. The dealer will tell you whatever they have to in order to make the sale.

sherdep · 02-02-2011, 09:20 PM

another thing to add is when I bought my 04 Dodge Ram 1500 4x4 it had a sheet that says not to tow a 5th wheel - not sure if your Ford came with that documentation or not.

also keep this in mind - you might not want to go to the max range of the combined tow vehicle and trailer combined - you might be able to pull it fine but stopping it is another ball game -since we have half ton trucks the brakes are not up to par to stop a heavy beast.

**Herk7769** · 02-03-2011, 06:59 AM

Quote:

Originally Posted by Rselzler

Researching some TT's now. I'm glad I found this forum as otherwise I'd surely have believed in the dealers sales pitch because I really wanted to believe. Think I'll go with a TT and save the 5th wheel dream for another day.

Thanks ALL!

You are not the Lone Ranger in that. Confidence men know that fact very well. You can not fool a sceptic. (Well you can, but it is harder). People WANT to believe there is a million dollars at the end of the rainbow without actually having to save or work for it. That makes them easy marks for Nigerian Scammers and State Lottery ticket sellers.

preacherpaul · 02-03-2011, 07:17 AM

We've been camping several years now and have upgraded from tent, to pop-up, to small TT, to large Tt and now to fifth wheel. Our son works for a RV Dealer and is responsible for the upgrades. He is also responsible for upgrades in trucks. My advice is start with a big truck, to save a lot of frustration and money.

MtnGuy · 02-03-2011, 08:40 AM

Quote:

Originally Posted by sherdep

also keep this in mind - you might not want to go to the max range of the combined tow vehicle and trailer combined - you might be able to pull it fine but stopping it is another ball game -since we have half ton trucks the brakes are not up to par to stop a heavy beast.

I think that is good advice. I bought a trailer that weighed 1/2 the weight of my listed maximum tow capacity, and now ready for camping it is at 57% of my maximum tow capacity. I can get things up to decent speed at uphill interstate entrances without over reveving, My transmission temperature will get to 210F on some of the mountain passes around here. I am comfortable with that, and the truck tows it great, but I know that I would not want to go to 100%.

Also, read up trailer length vs. tow vehicle wheelbase discussed on many forums here. The "suggested" safe maximum trailer length in feet is the truck wheelbase in inches divided by 5. According to that equation, my 28.5' trailer length is the maximum that I would want to pull with my 145" wheelbase truck.

edman87k5 · 02-03-2011, 09:35 AM

There is a big difference in being able to pull somthing and pulling it comfortably. Most 1/2 ton trucks with even a v6 will in fact pull most trailers out there, it will however be a very unnerving experience that will greatly shorten the life of the truck and possibly that of the driver or some other motorists.
Take it from someone who learned the hard way anout towing witout enough truck (I wrecked a 1/2 tone reg cab swb with utility trailer and another vehicle loaded onto trailer).
ALWAYS go with more truck than you think you need!
No way I would pull a 5th with ANY 1/2 ton. It will not hold up long with that kind of load.
Remember, the tow ratings are set my the manufacturer, there is NO standard by which they are set. Comparing truck a tow rating to truck B and C is almost pointless because they are not measured by any standard to get those numbers. Manufactures put a number on them that they think will cover their butt and that the running gear will hold up to for a while.
Also, you added larger tires to your truck that would struggle to comfortably handle that weight even with stock tires, did you even think about regearing to make up for the loss? Going up 1 or 2 inches in tire size is slightly noticeable during regular driving, but makes a huge difference when the weight is doubled by adding a trailer not to mention the added wind resistance.

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