Buying Guides, RV & Trailer Guides
Spare Tire Cover Sizes for RV and Trailers: The Proven Complete Guide
Jun
Finding the correct spare tire cover sizes for RV and trailer setups is essential — yet often overlooked. RV and trailer spare tires sit exposed to sunlight, rain, and harsh weather for extended periods, making a properly fitted cover one of the most important protective accessories you can add to your setup.
This guide explains exactly which spare tire cover sizes for RV and trailer configurations apply across common setups, lists the most frequently used tire codes with their corresponding cover sizes, and shows you how to confirm the right size before ordering.
Why Spare Tire Cover Sizes for RV and Trailers Matter More Than for Other Vehicles
RVs and trailers face a unique set of challenges that make proper spare tire protection especially critical:
- Extended outdoor exposure: Many RVs and trailers sit parked outdoors for weeks, months, or entire seasons. During this time, the spare tire is continuously exposed to UV rays, temperature fluctuations, and moisture — all of which accelerate rubber degradation.
- Infrequent use: Because spare tires on RVs and trailers are rarely used, damage from prolonged exposure can go unnoticed for a long time. A tire that has been slowly degrading under UV exposure may appear fine visually but have compromised structural integrity when you actually need it.
- High replacement cost: RV and trailer tires are often more expensive to replace than standard passenger car tires. A properly fitted spare tire cover is a small investment that can prevent a costly premature replacement.
For these reasons, choosing the correct spare tire cover sizes for RV and trailer setups is not just about appearance — it is a genuine safety and cost-saving consideration.
Spare Tire Cover Sizes for RV: Class A, B, and C Motorhomes
Motorhome spare tires vary based on the class and size of the RV. Here are the most common configurations:
Class A Motorhomes
Class A motorhomes are the largest RVs and use correspondingly large tires. Spare tires for Class A motorhomes are often the same heavy-duty commercial tires used on large trucks.
| Tire Code | Overall Diameter | Cover Size |
|---|---|---|
| 295/80R22.5 | ~39.4″ | Outside standard range* |
| 275/70R22.5 | ~38.0″ | Outside standard range* |
| 225/75R16 | ~28.4″ | 28″ |
*Note: Very large Class A motorhome tires may exceed the standard 27″–35″ cover range. Always measure your specific tire before ordering.
Class B and Class C Motorhomes
Class B (camper vans) and Class C motorhomes are smaller and use more standard tire sizes that fall comfortably within the typical spare tire cover range.
| Tire Code | Overall Diameter | Cover Size | Typical Vehicle |
|---|---|---|---|
| 215/85R16 | ~30.4″ | 30″ | Class B van conversion |
| 225/75R16 | ~28.4″ | 28″ | Class C on Ford chassis |
| 235/80R17 | ~31.8″ | 32″ | Class C on Ram/Chevy chassis |
| 245/75R16 | ~30.5″ | 31″ | Class C mid-size |
Spare Tire Cover Sizes for RV: Fifth Wheels and Travel Trailers
Fifth wheel trailers and travel trailers use a wide range of tire sizes depending on the trailer’s length, weight rating, and manufacturer specifications.
| Tire Code | Overall Diameter | Cover Size | Typical Trailer Type |
|---|---|---|---|
| ST205/75R15 | ~27.1″ | 27″ | Small travel trailer |
| ST225/75R15 | ~28.3″ | 28″ | Mid-size travel trailer |
| ST235/80R16 | ~30.0″ | 30″ | Large travel trailer |
| ST235/85R16 | ~30.9″ | 31″ | Fifth wheel trailer |
| ST245/75R17 | ~30.5″ | 31″ | Heavy-duty fifth wheel |
| ST255/80R16 | ~31.1″ | 31″ | Large fifth wheel |
Notice the “ST” designation in trailer tire codes — this stands for Special Trailer. ST tires are designed specifically for trailer use and have different construction characteristics than passenger or light truck tires. The sizing method is the same, but always confirm by calculating the overall diameter from the specific ST code on your tire.
Spare Tire Cover Sizes for Utility and Cargo Trailers
Utility trailers — including cargo trailers, boat trailers, flatbed trailers, and enclosed trailers — typically use smaller tires than RVs and travel trailers.
| Tire Code | Overall Diameter | Cover Size | Typical Use |
|---|---|---|---|
| ST175/80R13 | ~24.5″ | Outside standard range* | Small utility trailer |
| ST205/75R14 | ~26.1″ | Outside standard range* | Light cargo trailer |
| ST205/75R15 | ~27.1″ | 27″ | Standard utility trailer |
| ST225/75R15 | ~28.3″ | 28″ | Enclosed cargo trailer |
| ST235/80R16 | ~30.0″ | 30″ | Heavy-duty cargo trailer |
*Tires smaller than 27 inches in overall diameter fall outside the standard spare tire cover size range of 27″–35″. If your utility trailer uses very small tires, measure carefully to confirm whether standard covers apply.
Key Differences When Choosing Spare Tire Cover Sizes for RV vs Passenger Vehicles
There are several important differences to keep in mind when selecting spare tire cover sizes for RV and trailer setups compared to standard passenger vehicles:
ST vs LT vs P Tire Designations
RV and trailer tires often carry the “ST” (Special Trailer) designation rather than “LT” (Light Truck) or “P” (Passenger). While the sizing calculation method is the same, ST tires of the same labeled size as an LT or P tire may have slightly different overall diameters due to differences in construction and load rating. Always calculate from the full code rather than assuming equivalence.
Long-Term Storage Fit
For RVs and trailers that sit parked for extended periods, snug fit is especially important. A loose cover that allows wind to get underneath will shift, flap, and wear out much faster during long-term storage than during daily driving use. Choosing the exact matching size rather than sizing up is particularly important for storage applications.
UV Protection Priority
For RV spare tires, UV protection is the primary function of the cover rather than appearance. A properly fitted, UV-resistant cover significantly extends spare tire life during long outdoor storage periods — which is why getting the size exactly right matters more here than for daily-driven vehicles.
How to Confirm the Correct Spare Tire Cover Size for Your RV or Trailer
- Locate your spare tire. On most RVs and trailers, the spare is mounted externally — on the rear, underneath the chassis, or on a rear rack. Identify exactly where yours is stored.
- Read the full sidewall code. Find the complete tire code printed on the sidewall. Note the ST, LT, or P designation and the full code — for example, ST235/80R16.
- Calculate the overall diameter. Enter the code into a free online tire size calculator to get the overall diameter in inches. Alternatively, measure directly across the tire from tread edge to tread edge.
- Choose the closest matching size. Match the diameter to the nearest available cover size. For storage applications, choose the exact match rather than sizing up when possible.
- Confirm the camera hole option. Most RV and trailer spare tires do not have backup cameras mounted through them. Choose No Camera Hole unless your specific setup requires otherwise.
Frequently Asked Questions
What is the most common spare tire cover size for RVs?
The most common spare tire cover sizes for RV Class B and Class C motorhomes fall in the 28″–32″ range. Travel trailers and fifth wheels most commonly use 27″–31″ covers. Class A motorhomes may require sizes outside the standard range depending on their specific tire configuration.
Do RV spare tires need covers more than car spare tires?
Yes — significantly more. RV and trailer spare tires are exposed to prolonged outdoor conditions that dramatically accelerate UV degradation compared to daily-driven vehicles. A spare tire on an RV parked outdoors for six months receives far more UV exposure than a spare tire on a daily-driven SUV over the same period.
What does ST mean on a trailer tire?
ST stands for Special Trailer. These tires are specifically engineered for trailer use with stiffer sidewalls and higher load ratings than passenger or light truck tires. The sizing method — reading the code and calculating the overall diameter — is identical to other tire types.
Can I use a regular spare tire cover on my trailer’s ST tires?
Yes. Spare tire covers are sized by overall tire diameter regardless of whether the tire is designated ST, LT, or P. As long as you measure the overall diameter of your ST tire correctly and choose the matching cover size, a standard spare tire cover will fit and protect your trailer tire correctly.
Final Thoughts
The correct spare tire cover sizes for RV and trailer setups vary widely — from 27″ for small utility trailers all the way to sizes exceeding the standard range for large Class A motorhomes. For most travel trailers, fifth wheels, and Class B/C motorhomes, the 27″–32″ range covers the majority of configurations.
Measure your specific tire, confirm the overall diameter, and choose the matching cover size. For RV and trailer applications in particular, a properly fitted cover provides meaningful long-term protection that far outweighs its cost.
For the complete breakdown of all available sizes from 27″ to 35″ — including measurement methods, size charts for Jeep and SUV owners, and guidance on the 34″ V2 option — read our full sizing guide below.
👉 How to Choose the Right Spare Tire Cover Size (27–35 Inches) — Complete Guide
For RV and trailer tire safety standards, refer to the NHTSA tire safety guidelines — the official U.S. government resource for tire maintenance and vehicle safety.
Ready to protect your RV or trailer spare tire? Browse our full collection of custom spare tire covers, available in sizes 27″–35″ for motorhomes, travel trailers, fifth wheels, and utility trailers.