Bronco · How-To · Jeep · RV · Sizing Guide · Spare Tire Covers · Nov 07, 2026

How to Measure Your Spare Tire for a Tire Cover

Why the Right Size Matters

A spare tire cover only looks good and stays put if it's made for your tire. Too big and it flaps on the highway. Too small and it won't stretch over the tread. Every Goats Trail spare tire cover is made to order for the exact tire size you choose, so getting that size right is the most important step.

The good news: your size is printed right on the tire. Here's how to find it, read it and pick the right cover for your Jeep®, Bronco, RV or camper.

Step 1: Find the Numbers on Your Spare

Look at the sidewall of your spare tire, not the tires on the ground. Many vehicles carry a spare that's a different size from the other four, especially after a lift or a tire upgrade. Somewhere on the sidewall you'll see a code like this:

255/75R17

Write the whole code down. That's the number you'll match when you order.

Step 2: What the Numbers Mean

255 is the tire's width in millimeters.
75 is the aspect ratio: the sidewall height as a percentage of the width.
R17 means a radial tire on a 17-inch wheel.

All three numbers matter. Two tires on the same 17-inch wheel can be very different heights, so the wheel size alone isn't enough.

How tall is your tire?

If you're curious about your tire's overall height, here's the math: multiply the width by the aspect ratio, convert to inches, double it and add the wheel size. A few common examples:

Tire size	Approximate height
255/75R17	About 32 inches
285/70R17	About 32.7 inches
315/70R17	About 34.4 inches

You don't need to do this math to order. Just pick the code that matches your sidewall.

Step 3: Choose Your Size When You Order

Every spare tire cover has a Size option listing the most common sizes, for spares on 14-inch to 18-inch wheels. Choose the one that matches your sidewall exactly.

Don't see your size? Choose Custom Size and enter the code from your sidewall. Custom sizes cover larger tires too, including 37-inch and up. If you're unsure, contact us before you order and we'll help you pick.

Step 4: Backup Camera or Not?

Newer Jeep® Wrangler JL and Ford Bronco models have a backup camera mounted in the center of the spare. If yours does, choose the style Cover with back up camera for JL/Bronco. It has a cutout so the camera can still see. Everyone else should choose Cover without back up camera.

Bronco Owners: Check Your Trim

Factory tire sizes vary across the Bronco lineup, from the Base and Big Bend to the Badlands and Wildtrak. Use our Bronco factory tire size chart as a starting point, then confirm against your spare's sidewall, especially if you've upgraded your tires.

RV and Camper Owners

Spares on RVs, travel trailers and campers are often smaller tires on 14-inch to 16-inch wheels. The same sidewall code applies. Browse our RV spare tire covers or pick any design and choose your size.

Common Sizing Mistakes

Measuring a road tire instead of the spare. Always check the spare itself.
Ordering by wheel size only. "17-inch" isn't enough. You need the full code.
Forgetting a tire upgrade. If you swapped to bigger tires, your spare may have changed too.
Skipping the camera option. JL and Bronco owners with a spare-mounted camera need the cutout style.

Good to Know Before You Order

Every cover is made to order in the USA on marine-grade vinyl, with UV inks printed seam to seam and a strong elastic cord for a snug fit.
Covers come with a two-year warranty.
Because each cover is made for your tire, covers can't be returned for a change of mind. If one arrives defective, damaged or not as ordered, email support@goatstrail.com within 7 days of delivery with photos and we'll make it right.
Made-to-order items usually ship within 3 business days.

Installing is quick: see our sizing and install page for the how-to video.