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Having the Best RV Wheel Base Ratios Can Save Your Life

Updated on April 5, 2016
TIMETRAVELER2 profile image

I am an avid RV enthusiast who has traveled, lived, workcamped and volunteered nationwide for more than 50 years and am still going strong!

If you own a motor home or camper, or plan to purchase one, your safety can depend on having the best possible wheel base ratios.

If the location of your unit's wheels is not correct, your vehicle will not handle well and will be more prone to accidents because the risks of roll overs will be greatly increased.

Some people assume that the more expensive a coach is, the safer it is, but even many luxury motor homes have unsafe wheel base ratios. The only way to know is to learn the formulas and use the right techniques for measuring before you ever make a purchase.

This article explains this issue in detail, so make sure you read it all the way to the end. Your life and the lives of those you love could depend on it!

This coach has a good ratio.
This coach has a good ratio. | Source

Correct RV Wheel Base Ratios Equal Safety

Improper tire pressure, load distribution problems and weather and highway conditions are generally blamed for recreational vehicle accidents. Sometimes the blame is misplaced because the real is just as likely to be an coach’s wheel base ratio.

  • If your RV handles rough and leaves you with a fair amount of road fatigue, you need to take out your measuring tape and get busy
  • If you discover that your wheel base ratio is too low, you may be risking your life every time you drive your unit.

This coach has an excellent wheel base ratio and therefore drives well and is safer to own.
This coach has an excellent wheel base ratio and therefore drives well and is safer to own. | Source

Longer Is Safer

Wheel base ratio basically deals with the way the tires and axles are placed on the main chassis of a coach. Short ones, meaning those that have less distance between them, create a number of problems because they make the rig more difficult to drive. This leads to driver fatigue, stress and accidents.

Coaches with this type of problem have a longer rear overhang which causes the RV to "swing wide" when turning and can cause it to sideswipe anything that gets in its path. It also leads to a feeling of being "pushed" sideways when tractor trailers and other heavy vehicles pass the coach on the road.

Short ratios also make travel units less stable. This can cause rollovers, especially in rigs that have unbalanced loads as often happens when single side slide rooms are part of the structure.

RV Loading and Packing Tips talks about other issues that can also upset the balance and make this situation even more dangerous. Make sure to read it.

Calculated Industries 4020 Measure Master Pro Measurement Conversion Calculator
Calculated Industries 4020 Measure Master Pro Measurement Conversion Calculator

A measurement converter calculator will help you to determine RV wheel base ratio easily and quickly when you are searching for a safe RV.

 

Measurement Formula

Below is the formula to use for figuring the numbers. These will do the proper measurement on any recreational vehicle, but are most effective when you use them for motor homes because this is where they can provide the greatest safety benefits.

When you are following these directions, ask someone else to help you because it takes two to hold a long length of measuring tape stable enough to get true figures.

It is also a good idea to keep a measurement conversion calculator handy so that you don't have to make guesses when converting feet to inches. This can become confusing, so it is better to be safe than sorry.

You will also need an extra long measuring tape that will reach from the center of your front wheel to the center of your rear wheel. It is very important to keep it tight, otherwise your numbers will be incorrect. This product will come in handy for other projects as well, so it's good to have on hand, anyhow.

Here is what you need to do:

  1. Measure the entire length of the RV, including bumpers.
  2. Measure the distance from the center of the front tire to the center of the rear tire.
  3. Convert the feet into inches by multiplying by 12.
  4. Divide the length of the wheel distance by the length of the RV.
  5. Multiply that figure by 100.

For example, if your coach is 38 feet long and the distance between the center of its front and rear tires is 20 feet, you would

  1. Multiply 38 by 12 to get 456 inches.
  2. Multiply 20 by 12 to get 240 inches.
  3. Divide 240 by 456 to get .526 inches.
  4. Multiply .526 by 100 to get your wheel base ratio which is 52.6 inches.

This number is on the low side, but is still considered by some to be safe. Any figure above 50 inches is acceptable, but the higher the better. The rule of thumb from the RV Industry is 60 inches or more to maximize highway driving safety.

Stanley 34-790 100-Foot Open Reel Fiberglass Long Tape Rule
Stanley 34-790 100-Foot Open Reel Fiberglass Long Tape Rule

Use a long measuring tape to help you learn the wheel base ratio of any RV. These are good to carry with you when searching for a unit to buy and can also be used for other measuring purposes.

 

Each Model Within Brands Can Be Different

If you visit a dealership, take a long measuring tape and calculator with you to check and compare the ratios of different units.

Do not assume that because one model of one brand has good numbers that the others will also have them. Each coach, even within brands, measures differently.

When checking your figures, you will no doubt notice that the larger and more costly motor homes tend to have the higher, and thus safer, wheel base ratios, but this is not universally true. Some less expensive units can have acceptable and safe measurements as well, so price is not always a determiner of safety.

Another motor home with an acceptable wheel base ratio, but not quite as good as the ratio in the first photo.  The front wheels are a bit too far forward. It is more difficult to drive for that reason.
Another motor home with an acceptable wheel base ratio, but not quite as good as the ratio in the first photo. The front wheels are a bit too far forward. It is more difficult to drive for that reason. | Source

Measure Before You Buy

When you are shopping for motor homes or campers, nobody is going to share information about this issue with you. Salesmen do not want you to know about it, and, in fact, many of them do not even have this information themselves. This is one item you must learn about on your own.

By reading this article, you have done that, and you now understand why RV wheel base ratio is such an important issue.

  • If you are interested in purchasing an RV, you would be wise to get the figures before you buy .
  • If you already own a unit, find out now if it is safe.

Your life may depend on doing this.

Video Of Actual RV Roll Over On Highway

If you own a motor home, do you know your wheel base ratio?

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© 2013 TIMETRAVELER2

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  • TIMETRAVELER2 profile image
    Author

    TIMETRAVELER2 3 years ago

    wilderness: 52 is not bad, especially if your unit is short. Most people don't know about this safety issue, and they are the ones you often see overturned on the side of the road! Thanks for stopping by and commenting. I'm always happy to meet another RVer!

  • wilderness profile image

    Dan Harmon 3 years ago from Boise, Idaho

    Interesting, and something I had never considered. I just knew I didn't want a hangover half way to China.

    I see that my little shorty (only 26' long) comes to 52; I'll have to satisfied with that. Especially as another 2' of wheelbase would make a rather odd motorhome and increase the turning radius considerably.

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