MPG Halved by Boler

[Byron Kinnaman]

Originally Posted by mcbrew

Not me... The guys as Goodyear.

Now reconcile this:
When I purchased my Scamp it "Load B" tires on it. The stickers on the sides of the Scamp say inflate to 35 psi. My Scamp weighs 1700lbs on the axle. If was evenly divided that 850lbs per tire. According t the chart that would be around 25psi. Note also that the maximum tire pressure for "Load B" is 35 psi, the same pressure as indicated by Scamp.

I would like to know what the new 13' Scamps say to inflate the "Load C" tires to.

[Andy B]

Originally Posted by Byron Kinnaman

And here's what Carlisle has to say.

Always keep the tire manufacturer’s maximum recommended air pressure in all your tires, including the spare. This is an important requirement for tire safety and mileage. Tire sidewall stamping information will tell you the recommended cold air pressure.

Here is what Carlisle also has to say in the same link that you provided:

Review tire sidewall stamping information and the vehicle owner’s manual for the vehicle load limits and proper tire inflation.
Never exceed the maximum load rating stamped on tire sidewall of your tire or the maximum vehicle load rating, whichever is less. Make sure the load is spread evenly on all tires so that no single tire is overloaded. Tongue weight, tongue height and especially load leveling hitches must be set properly to avoid overloading your trailer tires.

It seems that Carlisle is contradicting themselves on the same document.

[Byron Kinnaman]

Originally Posted by Andy B

Here is what Carlisle also has to say in the same link that you provided:

Review tire sidewall stamping information and the vehicle owner’s manual for the vehicle load limits and proper tire inflation.
Never exceed the maximum load rating stamped on tire sidewall of your tire or the maximum vehicle load rating, whichever is less. Make sure the load is spread evenly on all tires so that no single tire is overloaded. Tongue weight, tongue height and especially load leveling hitches must be set properly to avoid overloading your trailer tires.

It seems that Carlisle is contradicting themselves on the same document.

Andy are trying to equate load rating with air pressure? It's not the same thing.

[Andy B]

Originally Posted by Byron Kinnaman

Andy are trying to equate load rating with air pressure? It's not the same thing.

Yes, they are not the same thing, however they are directly proportional. Carlisle provides a chart of load limits vs tire pressure at the same link and also has the following quote:

Therefore, a load range C tire is at its peak load capacity when inflated to its maximum pressure of 50 psi. In range D, you need to be at 65 psi to handle the increased load capacity. Load range E tires must be set at 80 psi.

Both these indicate a direct relationship, but they say the maximum pressure must be used and also say to use the lower load rating.

[gmw photos]

There is at least one tire manufacturer ( and I can't find the link right now, sorry ) that states their ST tires should always be run at the max pressure on the sidewall. They state that it has to do with the design of the tire needing the high pressure to maintain sidewall stiffness to help in not only keeping the tire cool, but to minimize sway.

Here is a general observation on my trailer tires. And first here is my disclaimer: this is just one data point of one user on one specific trailer and brand of tires.....so as always, YMMV !

But, my thoughts are this, some folks claim that running a tire at max pressure, when there is not enough load on it to warrant that inflation, will result in "wearing in the center of the tread" that is typical of over inflation. I understand their theory but at least in my case that is not happening. I have 7040 pounds of carrying capacity ( 4 x 1760 pounds at 50 psi ). My camper weighs 3780 pounds. About 3300 of that is on the tires. So.....according to the pundits, I have no need to be at 50 psi. And yet the tires are showing just a very slight amount of wear, and more important, it's exactly even across the tread. About 5000 miles on them now. So I am not seeing what would be called an over inflated wear pattern, even though the tires are only running at 47% of their rated capacity.

I'm going to keep running them at 50psi. It's working, and they run at typically about 10 to 15 degrees above ambient air temp, according to my non-contact IR thermometer.

....all of which has really kind of gone off topic that the OP started this with. But regarding inflation, I think that even those who recommend running low inflation pressures, would admit that it will result in using more fuel. It is pretty well established as fact that higher inflation pressures reduce rolling resistance.

So to the OP, regarding getting best fuel economy as relates to the trailer tires, my recco would be radial trailer tires inflated to the "proper" inflation. You yourself can choose how to decide "proper" inflation.

[Mike Magee]

I have a tandem axle (7000 lb. capacity) cargo trailer that I start the day at about 3500 lbs and gradually unload to empty (about 1500 lbs). My tire store recommended running the (50 psi max trailer) tires at about 35 psi for best wear. They said that based on the trailer's weight, if I kept them at 50 the center of the tread would wear before the sides of the tread. Based on how they actually wore, I've found that 40 psi seems to be about right (they were close).

[mcbrew]

For the record, I did not talk about tire wear. My biggest concern with over-inflated tires is bounciness. A lot of you folks with big trucks probably don't notice it, but you will in a car. I can tell that with MY trailer, there is a lot of bounce when inflated above 30 PSI. There is no doubt in my mind that this is wearing on the frame, coupler, and hitch more than it needs to. It also tosses my belongings around the Scamp. Lowering it to the recommended 15-20 PSI has solved this problem. As for mileage, I got 24 MPG on my last long trip with the Scamp. I doubt it would have been any higher with overinflated tires.

I'm not recommending low tire pressure. I'm recommending PROPER tire pressure. However, I'm not trying to change anyone's mind. Everyone here has decided what thy want to do... What data points they trust.... Which experts they want to believe. I think this is the last time I will talk about it publicly.

[Byron Kinnaman]

Originally Posted by mcbrew

For the record, I did not talk about tire wear. My biggest concern with over-inflated tires is bounciness. A lot of you folks with big trucks probably don't notice it, but you will in a car. I can tell that with MY trailer, there is a lot of bounce when inflated above 30 PSI. There is no doubt in my mind that this is wearing on the frame, coupler, and hitch more than it needs to. It also tosses my belongings around the Scamp. Lowering it to the recommended 15-20 PSI has solved this problem. As for mileage, I got 24 MPG on my last long trip with the Scamp. I doubt it would have been any higher with overinflated tires.

I'm not recommending low tire pressure. I'm recommending PROPER tire pressure. However, I'm not trying to change anyone's mind. Everyone here has decided what thy want to do... What data points they trust.... Which experts they want to believe. I think this is the last time I will talk about it publicly.

I think it was Ford Explorer that tried to use lowered tire pressure to improve ride.

[841K9]

Originally Posted by Byron Kinnaman

I think it was Ford Explorer that tried to use lowered tire pressure to improve ride.

Crappy drivers who did not maintain the posted tire pressure and expected a truck to handle like a sports car.
Rangers had the same suspension and drive train while running on similar tires.

Tires are a very active part of the vehicle's suspension. The sidewalls are supposed to flex and absorb most of the small road variations.

[mcbrew]

Yes.... AGAINST the recommendation of the tire manufacturer.

[gmw photos]

Just a thought here regarding trailer 'bounciness'. Those that are experiencing that might want to look closely at the trailer suspension. Older torsion axles often 'collapse'. I've seen some that are just just sagging somewhat, and I've seen others that have dropped essentially to the bottom of their travel. A sacked out suspension will result in a bouncy ride. Take a look at an older Airstream that is in need of restoration. Almost every one of them is bottomed out as they sit there.

One of the differences in ST tires is they are designed to have sidewalls that are stiffer than passenger tires. One advantage of this is they are less likely to sway, but a bigger advantage is that on a tandem axle setup, there is considerable 'sidewall twisting' going on as you corner. This sidewall flex occurs in a way that the tire manufacturers claim can be destructive to a passenger car tire.

Having said that, here's a another ( probably useless ! ) data point for you all: I come from the world of horses, and I can't begin to tell you how many tandem axle horse trailer I see all the time that are running around on used car tires. Folks use them because they are an inexpensive alternative. Surprisingly ( or not ? ) these tires are actually fairly trouble free from what I see and hear.

YMMV.

ps. leaf spring suspension can sack out too. Leafs can be rebuilt fairly cheaply with good results. If rebuilding leaf springs, check with a spring shop. Many big cities have these shops as it is still common in the trucking industry to fix/repair/re-arch leaf springs.

[841K9]

Originally Posted by gmw photos

ps. leaf spring suspension can sack out too. Leafs can be rebuilt fairly cheaply with good results. If rebuilding leaf springs, check with a spring shop. Many big cities have these shops as it is still common in the trucking industry to fix/repair/re-arch leaf springs.

Especially if it is a truck with lift blocks.
All spring or nothing.

[James Hutt]

I have pulled a 13 foot boler for several thousand miles, some of which was in mountain country and my gas mileage never dropped more than 20%. Sounds as though something may be binding or interfering with the pull. Should check it out.
Best of Luck,
Jim

[Borden]

Car is rated 5.7L per 100km (41.27mpg US) and we are getting 8.4L to 11.2L per 100km (21-28 mpg US) do not know what effect a head wind would do to us yet. Will be going up the Bruce Peninsula tomorrow from Owen Sound and just did a fill-up at Rockford while towing home will be able to do an accurate estimate "We push a lot of air" thank goodness we are well rounded!

Originally Posted by xichael

We just took our new Boler on her maiden voyage and were shocked to see the MPG meter on our '05 Caravan reading 11-15, where it would normally be 24-27.

Last summer I towed a utility trailer which weighed roughly the same, but was about 3 feet shorter, and it had little effect — maybe 2 or 3 MPG.

This means it's entirely a problem of aerodynamics. Really, really bad aerodynamics.

I really hope there are solutions to this, because otherwise we'll probably have to give up the dream and sell the Boler...

[RogerDat]

I used to see a loss in gas milage from my front wheel drive car if I put too much weight in the back. I was essentially losing traction. It was not the total weight it was how it was pushing down the back and reducing weight on front drive tires.


With trailer hitched to car on level ground stand back and look. Does the car appear to have any upward slant toward the front?


If so You might want to check your hitch weight, and what weight you carry in the rear of your car. To some extent you can put more weight behind the axle and reduce hitch weight but you need to keep 10% of the total weight of trailer on the hitch to avoid sway and other unpleasant behavior by your trailer.


Overdrive gear is a big factor in the milage that high mpg cars get on highway. So when you turn off / disable overdrive to tow you can expect some mpg loss. If you don't turn off overdrive then transmission will be shifting everytime the road inclines even a little up or down and that will hurt you mpg. And probably your transmission.


If you have a tach watch your rpm's at your towing speed with and without trailer. Our v6 Escape has to turn over 500 rpm faster at 55 mph (88.5 kph) to handle a 13 ft Scamp in tow. That is a 3.0L engine.

Last but not least the mpg meter in the dash of cars may not be accurate, especially in "odd" situations. Only thing that will really tell you what you are getting is fill up, odometer reading, and second fill up so you can do the math on actual fuel used for actual miles driven.

[841K9]

Originally Posted by RogerDat

Overdrive gear is a big factor in the milage that high mpg cars get on highway. So when you turn off / disable overdrive to tow you can expect some mpg loss.

You should never tow with overdrive engaged in a regular automatic transmission(Car, Minivan, "SUV" etc). It will overload the transmission and cause a premature failure. Hitting the overdrive cancel button will increase line pressure, disable overdrive and delay all shift points. This does hurt fuel economy, but it will extend the life of your transmission.

Remember that front wheel drive vehicles are not meant to tow every day. They're inherently weaker due to limitations from size and cost to manufacture.

[MC1]

Originally Posted by 841K9

Remember that front wheel drive vehicles are not meant to tow every day. They're inherently weaker due to limitations from size and cost to manufacture.

Not sure about this one. Our Nissan Quest had a very HD tranny that is almost identical as the tranny found in the full size RWD Infiniti Q45 sedan, (a V8 powered vehicle). Our van did a lot of towing and was still good at 435,000klms (300,000 miles).

[RogerDat]

Originally Posted by MC1

Not sure about this one. Our Nissan Quest had a very HD tranny that is almost identical as the tranny found in the full size RWD Infiniti Q45 sedan, (a V8 powered vehicle). Our van did a lot of towing and was still good at 435,000klms (300,000 miles).

As always YMMV

The different hardware combinations manufactures use in cars and trucks make for some unexpected results. Sometimes they do use an "available" design or component that is well above what they would design from scratch for that vehicle.

Always good to know about these "good deals". Do tend to think a car designed as a high milage front wheel drive passenger vehicle will generally have less designed in towing functionality. Frame strength = more weight, gear ratio for economy is not gear ratio for torque, surplus power in engine for towing is typically more weight plus more fuel consumption.

That is not to say there are not some vehicles that are very good options, that hit the sweet spot of dual use well, just that as a general rule it probably should not be expected as a given.

[MC1]

Roger, you summed it up nicely.

I have followed the FWD Mini Van towing craze for many years now.

The following vehicles seems to have very stout trannys.

Nissan Quest, Toyota Sienna's, Ford Windstars/Freestars and Honda Oddy's. I know of many examples of these that did extensive towing of various sizes of TT's without any tranny issues.

Note the Honda Oddys did have an issue with lubrication that a TB fixed. The problem was not a weak tranny as many suspect.

[Mike Magee]

I had a '96 Windstar, and we heard that the transmission was known to be, shall we say, less than great. Ours failed in '07 when a line ruptured and all the fluid ran out, ruining the tranny before the vehicle could be parked. Another tranny would have cost more than the van was worth, so we scrapped it.