I am an avid RV enthusiast who understands that my life and my safety depend on the condition of my coach's equipment.
If you own a motor home, travel trailer 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 risk of a rollover 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!
Correct RV Wheel Base Ratio Equals Safety
Improper tire pressure, load distribution problems and weather and highway conditions are generally blamed for recreational vehicle accidents, but sometimes the blame is misplaced because the real culprit is just as likely to be a 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.
Longer Is Safer
Wheel base ratio basically deals with the way the tires and axles are placed on the main chassis of a coach.
A short wheel base, meaning less distance between the axles, 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.
A short ratio also makes travel units less stable. This can cause rollovers, especially in rigs with unbalanced loads. A rig that includes single-side slide rooms is more likely to be unbalanced.
Below is the formula to use for calculating wheel base ratio. It will work on any recreational vehicle, but is most important for motor homes because this is where knowing the wheel base ratio can provide the greatest safety benefits.
To figure correctly, I always use a special conversion calculator. There are several types to choose from, but most are accurate and helpful. I also feel secure in knowing that the figures this calculator produces are correct and not just "almost guesses"!
I also use an extremely long Stanley measuring tape to make sure that no matter the length of the coach, I'm prepared! This brand is durable and trustworthy, which is what you need to be using for important issues such as measuring RV wheel base ratios.
Stanley measuring tapes are relatively inexpensive to buy and are worth every penny. If using them just one time helps to save my life, I'm happy!
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.
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.
Here is what you need to do:
- Measure the entire length of the RV, including bumpers.
- Measure the distance from the center of the front tire to the center of the rear tire.
- Divide the length of the wheel distance by the length of the RV.
- 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
- Divide 20 by 38 to get .526.
- Multiply .526 by 100 to get your wheel base ratio which is 52.6.
Any figure above 50 is considered acceptable, but the higher the better. The rule of thumb from the RV industry is 60 or more to maximize highway driving safety.
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.
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 Rollover on Highway
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: How do you measure a travel trailer?
Answer: From the outside of the front bumper to the outside of the rear bumper.
Question: How do I figure the wheelbase on a tandem axle?
Answer: Measure from the center of the rear wheel to the center of the front wheel.
© 2013 Sondra Rochelle
Sondra Rochelle (author) from USA on May 07, 2013:
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!
Dan Harmon from Boise, Idaho on May 06, 2013:
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.