Size Guide: Why Do RVs Have Such Small Tires?

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Take one look at the size of your RV tires, and you’ll likely feel perplexed as to why they’re so small. After all, an RV is a pretty big piece of equipment, right? How is a tire so small and still capable of lugging around something so large?

RVs have small tires because a smaller tire means less intrusion into the undercarriage space and wheel wells (=more space for you inside). Because of this, the RV retains more stability as well. Another reason these tires are so small is likely due to manufacturers cutting costs by using smaller tires during assembly.

The rest of this article is going to cover how RV type affects tire size. I’ll also show you how to find the correct tire for your specific vehicle. 

Are There Different Tire Sizes For RVs?

There are different tire sizes for RVs, and depending on the size and type of your RV, there is a specific tire size that best fits the vehicle. The size of your RV is also known as the “class,” which could be one of three options: A, B, or C. 

Class size is important to note as tire sizes are distinguished by using different class groups. Let’s take a look at them and which RV they are best suited for.

Class A Motorhomes

Class A is the largest tire available and is reserved for large RVs. They can support 15,000-30,000 lbs (6803.88-13607.77 kg). They can also fit on RVs up to 40 ft (12.19 m) long and are compatible with converted busses.

Class B Motorhomes

Class B tires are the smallest of the three options despite being the second letter. They will carry between 6,000-8,000 lbs (2721.55-3628.73 kg) and are best for RVs between 17-19 ft (5.18-5.79 m) long. Class B tires typically are fitted to van life and trucks.

Class C Motorhomes

Class C tires are mid-range size and can accommodate between 10,000-12,000 lbs (4535.92-5443.10 kg). Class C tires are typically used on RVs 20-30 ft (6.09-9.14 m) long and commonly fit heavy-duty vans and larger trucks.

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RV Tire Weight and Size Designations

When trying to determine how much weight an RV tire will hold, there are a few acronyms to keep note of:

  • UVW: This is the Unloaded Vehicle Weight. In other words, the weight of your vehicle at the time of manufacture is the UVW.
  • GCWR: GCWR is the Gross Vehicle Weight, or the vehicle’s actual weight when fully loaded.
  • CCC: The Cargo Carrying Capacity is the Gross Vehicle Weight subtracted from the Unloaded Vehicle Weight.
  • TW: TW, or “Tongue Weight,” is the vertical load amount on the trailer hitch.

How To Find The Correct Size For Your RV

Determining the correct size tire for your RV is as easy as consulting the owners’ manual. 

However, if the manual isn’t available to you, there are other ways to find that information. The most helpful way to find out is by finding the measurements posted on your existing tires, which can be found in a 12-digit code on your tire. If you have an old campervan, you can sometimes find instructions online on forums and communities. That’s how I manage to find the tire pressure for my old Hymer.

The code determines vehicle type, width, aspect ratio, construction, rim diameter, load index, and speed rating. It also lists the different measurements in that order. 

Here is a simple breakdown of how to read your tire measurements:

  • Vehicle type: The vehicle type is the first indication of the code, which is represented by a letter.
  • Width: After the code letter for the vehicle type is width, which is indicated by three numbers (or fewer depending on the size), followed by a backslash.
  • Aspect ratio: The aspect ratio is the number that comes after the backslash, and is usually a two-digit number.
  • Construction: After the aspect ratio will be a single letter, which determines the construction type of the tire.
  • Rim diameter: The next two digits after the construction letter will tell you the rim diameter. 
  • Load index: The two digits after the rim diameter is your load index.
  • Speed rating: The final digit of the code is your speed rating, and will be indicated by varying letters of the alphabet.

Determining the correct tire size can feel intimidating with all these letters and numbers, so the best course of action is to consult with a professional if you’re confused at all. 

Even the best DIYer can run into issues, and it’s better to be safe than sorry.

Also, a professional will be more equipped to tell you if they find anything wrong with your tires, which could be anything from a leak to dry rot to full-on replacement if necessary.

How To Determine the Age Of Your Tires

Regardless of the size, trailer tires typically last anywhere between 3-6 years

Because of the extensive weight they carry, along with the potential for long road trips, the small tires of an RV wear down easier. To find out how old your RV tires are, look at the sidewall of your tire. 

On one side, you’ll find the ID code designated by the Department of Transportation. This code will begin with “DOT,” followed by a series of numbers. The last four numbers of that code are the most important. 

These four numbers represent the week and year the tire was made. For example, if your tire’s last four digits are 0819, then the tires were manufactured during the eighth week of 2019.

The best way to ensure long-lasting tires is to take care of them and provide maintenance when necessary. Using tire covers will help prevent dry rot, and patching any leaks and holes will keep them in working condition until it’s time to switch them out.

Final Thoughts

Although it seems impossible for a small tire to support a heavy RV, the use of smaller tires helps balance out the vehicle. 

Depending on the size of your RV, the tires you should use will also vary by size. Knowing whether your RV is a Class A, B, or C vehicle will help ensure you get the correct size tire to support your RV.

If you’re ever in doubt of yourself, it’s always worth consulting with a professional. Second-guessing yourself isn’t worth it if that means you risk blowing out your tire or damaging your RV’s integrity.

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