Spare Tire Covers: How to Measure and Choose the Right One
A spare tire cover looks like a simple accessory, but choosing one well takes more than matching a vehicle type on a product label. The right cover depends on the tire's actual dimensions, the carrier that holds it, how well the material handles sun and rain, and whether you can still reach the spare when you need it. Here is how to measure, compare, and fit one.
What a Spare Tire Cover Can Protect
An exterior spare rides in the open for months or years, so its rubber is exposed to constant sunlight, road grime, rain, and winter slush. A cover acts as a barrier over the tread and outer sidewall. It cuts down the direct ultraviolet exposure that can dry out and weather rubber over time, and it keeps mud and salt spray off the most visible surfaces. That protection only extends as far as the cover wraps. Depending on its design and depth, the carrier bracket, the back of the wheel, and parts of the inner sidewall often stay exposed.
A cover also hides the tire, which cuts both ways. It cannot tell you whether the spare holds pressure, whether the rubber is cracking, or whether the tire has aged past safe use, so you still need routine pressure and condition checks. When shopping, focus on four questions. Will it fit the tire's real dimensions? Does the material suit your climate? Do the closures hold it securely? Can you remove it easily when you need to inspect or use the spare?
Measure Tire Diameter and Width Before Ordering
Park on level ground with the engine off and the spare safely within reach. Run a tape measure across the face of the tire through the center of the wheel, from the outer edge of the tread on one side to the outer edge on the other. That is the overall tire diameter. Next, measure the width across the tread from sidewall to sidewall. Note any lug nuts, carrier arms, or brackets that stick out past the tire face, since the cover needs extra depth to enclose them.
Sidewall size markings help, but read them carefully. The last number in the size is the wheel diameter in inches, not the diameter of the whole tire, so a cover ordered by that figure alone will be far too small. Compare the sidewall size and your own measurements against the cover manufacturer's sizing chart and its stated fit range. A cover that sags or spins needs a smaller size. One that you have to force over the tread is too small and will strain its seams. Don't assume every brand allows the same amount of stretch.
Check Hard and Soft Cover Construction
Soft spare tire covers are made from flexible fabric or vinyl, sewn into a round face panel and a band that wraps around the tread. Most rely on an elastic hem that pulls in behind the tire, and some add a drawstring, hook-and-loop tabs, or retention straps. When comparing them, look closely at the seam stitching, how the hem is finished, and whether you can tighten the closure. Hard spare tire covers use a rigid shell instead, usually held on by a retaining band, and some designs need fastening hardware made for a specific carrier.
Read material claims carefully. Stated UV resistance and water-resistant fabric describe how the material is treated, not how many seasons it will last in your climate. Check whether a lining could trap moisture against the tire, and what cleaning methods the manufacturer allows. Seams, hems, and any openings can all let water in. A cover mounted upright on a rear door sheds rain differently than one that sits low or at an angle, so any ventilation or drainage features should suit where your spare actually rides.
Confirm Fit and Access on Campers and RVs
A product labeled for campers or RVs is a starting point, not a guarantee of fit. Motorhomes and truck campers use a wide range of tire sizes and carriers, so the measurements described above still decide the size. Look at how the carrier holds the spare. Some mount flat against the rear wall, while others swing outward or sit on a bracket attached to the bumper. Then check clearance around rear ladders, storage doors, body panels, and the carrier's release or locking points, since a bulky cover can rub paint or block a latch.
Many rigs have a backup camera in the center of the spare or just above it. If yours does, compare the position and size of the cover's camera opening with your actual camera location before ordering. A misaligned opening can block the view or leave the edge of the lens exposed. Access matters too. You should be able to pull the cover off to check tread and pressure, and to release the spare from the carrier, without unbolting accessories or fighting straps that tangle in the carrier mechanism.
Check Trailer Mount Location and Surrounding Clearance
Trailer spares are mounted in more varied spots than most vehicle spares. A tongue-mounted tire sits near the coupler, jack, and safety chains. A bumper mount places it among the taillights, license plate, and wiring, and a side mount may sit close to fenders or compartment doors. Each position limits how deep and wide the fitted cover can be. Once the cover is on, check that it and any straps stay clear of the lights, plate, wiring, coupler controls, and safety chains, wherever those are nearby.
On camping and travel trailers, also make sure the cover doesn't block storage compartment doors, propane cylinders and their valves, or stabilizer jack controls, since you may need them at a campsite after dark. Confirm that the product is designed for an exposed spare in your mounting position and for use while towing, not just for parked storage. If getting a good fit would mean drilling, bending, or relocating a carrier or other mounting hardware, have a qualified installer look at the setup instead.
Secure the Cover and Keep the Spare Inspectable
Follow the cover manufacturer's instructions for its closure, whether that is an elastic hem, retention straps, a zipper, or retaining hardware on a hard shell. With the vehicle or trailer parked, walk around the spare and check three things. The cover should sit evenly with no gaps at the edge, every closure should be fully engaged, and there should be no loose strap ends that can flap or snag. Before driving off, confirm that nearby lights, cameras, latches, and controls are still unobstructed.
Clean the cover only with products approved for its material, and let both the tire and the cover dry before refitting so moisture isn't sealed against the rubber. Reassess the cover if you find tears, broken closures, cracking vinyl or shell material, dampness that won't clear underneath, or signs that it keeps shifting while you drive. If you see any damage on the tire, or you're unsure of the spare's age and condition, have a tire professional check it. A clean, well-covered spare can still be unsafe to use.