RV, Motorhome and Camper, TIRE Information and Specifications.
Motorhome and Camper Tires
The information in this article includes important reference data on Tires that are used on automobiles as well as your; RV, Motorhome, Camper, Trailer, Fifth Wheel and even Pop-Up campers.
The data here will help the reader understand tire markings and ratings when they need to replace their older or worn tires.
RV and Camper Tire Specifications
The tires on your RV are as specialized in their design as are those on a race car.
The ones on a race car are designed to operate at extreme speeds, and provide as safe a ride as possible.
And the tires on your RV are just as specialized, but they are designed to carry very large loads on diverse types of roads at various speeds and still provide as safe a ride as possible.
Be sure to know your tire size, tire age, and condition, and always replace them with the same/equivalent tires.
Keep in mind that as soon as tires are manufactured, they begin to age and degrade to one degree or other, depending on how they are stored and maintained.
There are several things you should do to assure that your tires are safe, and last a long time for you.
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Tire Specifications and what those Specs mean
RV’s use a wide range of tire sizes with many different specifications that the manufacturer selected to match your RV's design requirements.
When you replace your tires be sure to select tires that match these specifications.
Here are some of the marking you will see when you look at your RV tires, along with the definition of what they mean, for your reference.
But ...... Always check with your tire dealers for the latest recommendations, as the technology for tire construction is constantly changing:
RV Tire Size- (example = P245/ 70 / R 19.5 )
The first 3-digit number 245 is the tires Section Width. It indicates that the tire is 245 millimeters across from the widest point of its outer sidewall to the widest point of its inner sidewall.
The letters in front of the 3-digit number will indicate the following;
P= indicates it is a P-metric tire, and is used on passenger cars including; cars, minivans, sport utility vehicles and light duty pickup trucks (typically 1/4- and 1/2-ton load capacity).
Nothing = indicates If blank then the tire is a "Metric" size (also called "Euro-metric". Euro-metric sizes are equivalent dimensions as P-metric sizes, but usually differ slightly in load carrying capabilities.
T = this indicates that the tire is a "Temporary Spare" ("space saver" or "mini spare") and was designed to only be used temporarily until a flat tire can be repaired or replaced.
LT = indicates that the tire is a "Light Truck-metric" size and was designed to be used on vehicles that carry heavy cargo or are towing large trailers. These are for vehicles including medium and heavy-duty (typically 3/4- and 1-ton load capacity) pickup trucks, SUV’s and full-size vans. They are designed to provide reserve capacity to handle the additional stresses of carrying heavy cargo.
70 = The number after the slash, after the 3-digit number, a 70 here, is called it’s Section Height or Aspect Ratio. This tire size's sidewall height (from rim to tread) is 70% of its section width.
R = The letter after the Aspect Ratio indicates the type of tire construction. For instance, an R indicates Radial construction, while a D indicated a Diagonal or Bias ply construction, and if it is a B, this indicates it is a Radial Ply construction that is reinforced with belts in the tread area.
19.5 = The number following the type of construction letter indicates; indicates the tire and wheel diameter that are designed to be matched together. Tires with these numbers; have a rim diameter expressed in inches, such as;
(P225/50R16, as well as 8, 10, 12, 13, 14, 15, 17, 18, 19, 20, 22, 23, 24, 26 and 28) are called "inch rim" sizes, and are used on most cars, minivans, vans, sport utility vehicles and light duty light trucks. Also, tires and wheels that have a rim diameter expressed in "half" inch sizes; 14.5, 15.5, 16.5 17.5 19.5 21.5 and 22.5) are used on some heavy-duty trailers, heavy-duty light trucks box vans and Recreation Vehicles
NOTE: Tires and wheels with unique rim diameters should never be combined with traditional "inch rim" tires and wheels.
Trailer Tire Sizes
SIZE - ( ST 225 / 75 R 15 )
For trailers the breakdown of the numbers are as follows:
- ST - Special Tire for Trailer
- 225 - Cross Section in MM
- 75 - Aspect Ratio which is the section height divided by the section width
- R - Radial
- 15 - Rim Diameter in inches
Tire DOT Designations
The DOT designations - DOT MJ93 NBAW 0807
The DOT - NHTSA requires that Tire Identification Numbers be a combination of the letters DOT, followed by ten (1980's production), eleven (1990's production) or twelve (2000's production) letters/numbers that identify the; manufacturing location, tire size, manufacturer's code, and the week and year the tire was manufactured.
MJ93- The MJ indicates the Manufacturers Plant code, and the 93 indicates the government size and ply code.
NBAW- Indicates the Manufacturers production code.
0807- Since the Year 2000, the last 4 digits in this group indicate the week and the year of manufacture. Or 0807 indicates week-08 of year-07.
Notes on Tire Age and Longevity
All RV tires have a date code on them. It is generally recommended to replace any tire more than 6-years old regardless of the amount of tread remaining.
If your tires still have good tread and no signs of aging, especially in the sidewalls, and you still insist on continuing to ride on them, please keep a close and constant eye on them, and please never exceed the speed limit with Old tires on your RV.
You should monitor your tires, ALL of them, before and after every trip for unusual tire wear, and proper air levels.
An RV’s tires are very expensive, and you do not want to replace them any sooner than necessary.
So, inspect your tires often for the following potential hazardous problems:
- Uneven Tire Wear
- Cupping at the edges of the tire tread
- Nails imbedded in the tread of the tire
- Cuts in the sidewall of the tire
If any of these is evident, you should take your RV to your local tire dealer/service center that also services RV’s for resolution of the problem.
The Sun can play havoc with the condition of your tires and it can age them prematurely, and cost you a lot of money for early replacements, so take steps to avoid direct sunlight on your tires when possible, especially when your unit is in storage.
Notes to Extend your Tires Useful Life
There are several things you can do to help protect your tires and extend their useful life.
Keep your tires clean of dirt and debris and spray them with protectant sprays, available at your local Auto Parts store, that provide some screening of UV rays.
Raise the Tires-
When you are parking your RV for an extended period of time, place plastic or wooden blocks under the tires. This elevates the tires above the ground, and minimizes the tires' contact with moisture.
And, when you are parking your RV for an extended period of time, such as in storage for a few months, or at a campground for the winter, place Tire Covers on your outer tires, to shade them from the Sun and the Elements and they can last several years longer before they show signs of cracking and deterioration.
Warning: Buying Old Tires:
I was recently walking in one of the RV Parts Stores, which was actually one of the largest nationwide tire chains.
Heading towards the counter, I passed a sign that was touting the low price of their "New but Older Date Code" tires.
Well, I was shocked. Everyone knows when shopping for a used RV or any other vehicle, one of the first things you look at is the age and condition of the Tires on the RV.
And, as I have mentioned above, the material in RV tires begins to age and deteriorate, from the date they are made, thus the major reason for the required date code on tires.
So, how much of a discount do you need on your OLD/NEW tires to override your need for safety when driving your family down the road. What a stupid thing for a store to do!
Consumers Report Tire Buying Guide Video
A Good description of all of your tire markings
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© 2010 Don Bobbitt
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