RV & Trailer Spare Tire Cover Sizing Guide

A trailer tire cover only does its job if it actually fits, and getting the size wrong is the most common mistake RV owners make when ordering one. This guide covers the two ways to measure your tire, what the size ranges mean, and which material holds up best against sun, rain, and Atlantic Canada winters.

Why Cover Your Spare Tire

A spare tire that sits exposed on a bumper mount or under the trailer takes the brunt of UV exposure and road grime, even though it rarely rolls a mile. Sunlight breaks down rubber over time, leading to cracking and dry rot long before the tread wears out. A properly fitted cover blocks UV rays and keeps rain, snow, and dirt off the tire and rim, which extends the life of a tire you are counting on in an emergency.

Two Ways to Find Your Tire Cover Size

Option 1: Read the tire sidewall. Every tire has a size code stamped into the sidewall, showing width, aspect ratio, and wheel diameter. Match that code against a manufacturer's size chart, such as the ones used for Camco tire covers, and the chart will point you to the correct cover size.

Option 2: Measure with a tape measure. If the sidewall code is worn off or you would rather confirm the fit yourself, measure the tire directly. Make sure the tire is properly inflated first. Stretch the tape measure from the top center of the tire straight down to the bottom center to get the outer diameter, then measure sidewall to sidewall across the face of the tire to get the width.

Either method gets you to the same result: a diameter measurement in inches that you match against the cover's stated size range.

Common Tire Cover Size Ranges

Covers are sold in banded diameter ranges rather than exact inches, since a couple of inches of stretch or slack in the material covers the gap. Typical bands we carry include:

• 27 to 29 inches
• 30 to 32 inches
• 33 to 35 inches
• Single-fit sizes for larger spares, such as our 34 inch diameter Camco cover

Always round up if your measurement lands right on the edge of two bands. A cover that is slightly loose still protects the tire. A cover that is too tight will not stretch over the tread and rim.

Single Covers vs Matched Sets

Most trailer spare tire covers are sold as a single cover sized to one tire. If your trailer carries more than one exposed spare, or you are covering matching tires on both sides, look for covers sold as a set, such as our Camco Black Tire/Wheel Cover 24-26 inch (Set of 2), so the sizing and colour match across your trailer.

Material Options: Vinyl, Nylon, and Plastic

Vinyl is the most common material for RV-grade tire covers, including the Camco covers carried in our Wheels & Brakes collection. Heavy-duty vinyl holds up well against UV rays and sheds rain and snow without becoming brittle in cold weather, which matters through an Atlantic Canada winter storage season.

Nylon covers are lighter and less expensive, offering basic sun protection, but they do not seal out moisture as well as vinyl.

Plastic covers keep moisture out effectively but tend to get brittle and crack after repeated exposure to sun, especially compared to vinyl.

For year-round storage in this climate, vinyl is generally the more durable choice.

When to Replace Your Tire Cover

Swap your cover out if it has cracked, faded through to the point it no longer blocks UV, or no longer holds its shape snugly around the tire. It is also worth checking your cover size any time you change your spare tire size, since a cover sized for your old spare will not necessarily fit a replacement of a different diameter. If your wheel chocks are also showing wear, it is a good time to check both at once since they are stored in similar conditions.

Frequently Asked Questions

What size RV tire cover do I need?

Measure your tire's outer diameter and width, or read the size code off the sidewall, then match that measurement to the cover's stated diameter range.

How do I measure my tire for a cover?

With the tire properly inflated, measure straight down from the top center to the bottom center for diameter, then sidewall to sidewall for width.

Should a tire cover be tight or loose?

A slightly loose fit is fine and still protects the tire. Avoid a cover so tight it cannot stretch fully over the tread and rim.

What material lasts longest for RV tire covers?

Heavy-duty vinyl generally holds up best against UV exposure and cold-weather storage compared to nylon or plastic.

Do I need a cover for a spare I rarely use?

Yes. Spares sit exposed to the same sun and weather as your road tires, and UV exposure causes cracking and dry rot regardless of how many miles are on the tire.

Shop Tire Covers at The Trailer Guys

Browse our Tire Cover collection for Camco vinyl covers in the common size ranges above, or check the rest of our Wheels & Brakes collection for wheel chocks, hubs, and bearings. Stop by 745 Route 133 in Boudreau-Ouest and our team can help confirm your exact size in person, or read our axle and bearing guide for the next item on your wheel-end maintenance list.