The Age Old Question, How Many Pounds Of Air Shall I Put In My Tires?

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Well sir, I have never been accused of being terribly smart and politicaly astue, so here I go jumping from the frying pan into the fire on a subject that some have said in the forums is a dead horse and beaten to death. But there is more to the tire pressure story than just when will it fail or blow up. Or how much pressure to ad and when.

We all know that a tire that is under inflated will use more power to make it roll than a properly inflated tire. That is because of these factors:

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Valid Mileage Comparisons

The mail bag is getting full and it would be the polite thing to do to answer the questions and make room for more. Santa Skip wrote the following after I used the term Tommy Knocker:

“I spent my younger years exploring the ghost towns of CO, to me a tommyknocker was a little elf who lived down in the mine, if he liked you he would show you where the gold, (was) if he didn’t he would cause all kind of problems.”

One of the neat things about traveling is that you get to learn that an expression that you grew up with have different meanings regionally. But this is a new meaning of Tommy Knocker to me.

Chuck wrote the following after my comments on driving at 55 miles per hour:

“I’m posting this as a reality check. I’m getting better MPG at 68-72 mph (2200 rpm) than at 55 mph. I drive a F250 with a V10. With or without the 5th wheel trailer I get better mileage at a higher speed and higher rpm. At my last fill up I got 10.8 mpg. I traveled 107 miles with the 5th wheel trailer and 190 miles without the trailer. In the past if I drove at 55 I would get around 8 to 9 mpg. Has anyone else seen this type of mpg driving faster instead of slower?”

Under real world conditions it is almost impossible to get accurate fuel economy numbers. Back in the dark ages, about 1980 something, the EPA was in the process of certifying fuel savings devices. They invited a group of automotive writers to a test drive to provide the EPA with numbers of fuel economy improvement of the new Volkswagen E Shift light system. It was a computer controlled device that would turn a light on on the dash that would signal the driver when to up shift for best economy. The route was from the tip of Long Island to Newport, Rhode Island. Lots of rolling hills.

VW teamed up the drivers and it happened that Dan Holt, then a writer/editor with the Society of Automotive Engineers publication, and I drew the duty as partners. Now not to say that we were heavy, but between the two of us we exceeded the load carrying capacity of the car, not counting our luggage or our camera gear. Now as every one knows writers have imagination. Dan and I being both engineers decided that we would show some real fuel economy, and here is how we did it.

The first thing that we did was to eliminate rolling resistance. We stopped and pumped the tires up to 80 PSI. The car rode like it had Freddy Flintstone Hard Rock tires. Then we applied some simple junior high school physics. Gravity. We figured with our combined weight, the weight of the car, and gravity, that we could use the engine on down hill runs to get the speed up, and then coast up the next hill. Foot to the floor in high gear going down hill, put the tranny in neutral and shut the engine off for the uphill coast. In several instances on the run we were able to leave the engine off for several hills as well as seeing the tach hit red line in high gear.

VW controlled the record keeping of fuel in each car with a burette attached to the front bumper and at each fuel stop they measured fuel used and filled the burette to the full line and we ventured out again. Well Dan and I placed second in this 50 car run with around 100 miles per gallon. A couple of guys from one of the magazines out did us by a couple of miles per gallon. I think they ran a bit more air in their tires but they used the same techniques. We did show VW that we could get good mileage but it did little for the certification of the Up Shift Light. And we broke speed laws and really had a ball.

The moral of the story, which is a true story all the way, is that determining a difference in fuel economy means measuring apples against apples under like conditions with only one variable at a time. Driving cost over an extended period of time is a valid number.

Pet Travel Challenges

All of us like to travel with our pets when we can. It’s no fun for them (or us) when we have to leave them behind — even for a short time. Although traveling with pets has gotten easier and more fun with all of the pet travel products available on the market, we still encounter various challenges as we trek across town or across country. Read more

“Drive your Motorhome Like a Pro” DVD released

RV.net echoes the announcement of Mark Polk’s brand new DVD titled “Drive your Motorhome Like a Pro”, co-hosted with Lorrin Walsh, author of the book by the same name. As indicated in the press release, this DVD provides the tools to increase one’s awareness of driving motor coaches, and demonstrates unique driving techniques needed to become a safer and a more confident driver.

We thank our bloggers for their dedicated efforts to keep the RV community informed and entertained. Therefore, when we find out that one of our bloggers has released a new book or product, we help them spread the word.

RVing with pets and their unique needs

I would bet that most people who travel with pets have a canine along with them in the RV, car or plane. But there are a lot of folks who travel with their cats, birds and other pets as they head out for business or pleasure. The type of pet you travel with can have unique requirements for feeding, comfort, safety and other considerations. Birds, for example, have much more stringent travel needs than dogs. Some people would argue that cats are more difficult to travel with than dogs. Read more

Our SCARIEST RV Tow

Airstream RV Blog #47 - Towin’ and Backin’ from Sean Michael on Vimeo.

Before we bought our travel trailer, the thought of towing an RV was foreign to me. Heck, I’d never even owned a pickup truck before. So I faced a learning curve, one compounded by the fact I’d never really backed up an RV either. To newcomers, these two tasks can be very intimidating. But they need not be. Today I’ll write about our “most frightening” tow experience. In a future post, I’ll tackle my worst backing experience…

Although today’s video was shot in sunny San Diego, our most frightening towing experience happened a thousand miles away, in remote British Columbia. We were following a tip offered by a park ranger in Alberta. “If you want nice hot springs,” the ranger said, “check out Lussier Springs. It’s in British Columbia, down near Canal Flats.”

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Sway Control

When I bought my first new Travel trailer, I asked the dealer to give me everything I needed. As part of my tow package, they included a Friction Sway bar. I was very careful about hooking the trailer to the tow vehicle as I was instructed but I experienced really bad sway. I eventually tightened the sway bar down as tight as it would go which helped, but I still experienced sway. This was a problem because I was very stressed driving and really didn’t enjoy the drive.

I did everything I could to rectify this problem by moving things around inside the trailer to make sure it was well balanced, but I still had sway. I started researching all the methods of sway control. I decided that I wanted to drop the friction bar and do something else. I was a bit overwhelmed about all the options. There are quite a few schools of thought and different approaches to the same solutions. Read more

Unsprung Weight, Unlocking The Mystery

Lug Nuts latest blog on Aluminum Wheels was, as his usual product is, great. I have aluminum wheels on Rover, our 1990 Foretravel DP, and they are great. But there is one great advantage and that is that they are lighter as Lug Nut said. And as he said that reduces unsprung weight.

With Lug Nuts permission I would like to expand a bit on the mystery of unsprung weight other than the general weight reduction of the rig. Unsprung weight is the weight of the components between the springs and the ground. That includes the tire, wheel, bearings and hub, brake rotor or brake drum, caliper and pads, brake shoes and springs, wheel trim rings, lug nuts, and suspension members between the springs (or air bags), and the ground.

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Motorcycle Safety

Okay, yes this is about RVs and driving safety, because it is about RVers.  There are many RVers that are motorcycle enthusiasts.  In Canada, motorcyclists have been dragging their two-wheeled freedom machines out of storage for the last few weeks, and I am seeing more and more of them out on the streets again.  Those of you who live where you don’t get three feet of snow are lucky enough to ride your motorcycles year round.  Either way, we could all use a few reminders about motorcycle safety — even if you don’t ride one, as we all share the road.

Sadly, I investigate at least one fatality every riding season where a motorcyclist loses his (or her) life because of careless driving.  Usually, that carelessness is firmly on the shoulders of the victim himself.  These are typically young males who enjoy the adrenaline rush a fast motorcycle can give them for relatively few dollars compared to a sportscar that still wouldn’t come close to the acceleration of a motorcycle at 3x the price.  I can recall travelling west of Calgary on the Trans-Canada highway at 115 Km/h in my pickup, and being passed like I was standing still by a sportbike with a lone rider.  Doesn’t sound too uncommon until I tell you that he was only on the back wheel at the time!  Craziness!  That young man was one golf ball sized stone away from death. Read more

Air Disc Brakes May One Day Be On All DP’s

 On March 16^th. I did a write up covering some of the choices of supplement braking systems on today’s motor coaches, like Pac and Jake brakes.   I also did a piece the following week, on March 23rd, on real world application and techniques of same.   Well, this week’s topic will relate to those as we look at better braking systems for air equipped coaches.  

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