{"id":244100,"date":"2026-05-07T10:17:38","date_gmt":"2026-05-07T10:17:38","guid":{"rendered":"https:\/\/wheelshell.com\/blog\/how-to-measure-spare-tire-cover-size\/"},"modified":"2026-05-14T12:17:30","modified_gmt":"2026-05-14T12:17:30","slug":"how-to-measure-spare-tire-cover-size","status":"publish","type":"post","link":"https:\/\/wheelshell.com\/it\/blog\/how-to-measure-spare-tire-cover-size\/","title":{"rendered":"Come Misurare la Ruota di Scorta e Scegliere la Taglia Giusta del Copriruota (con Tabelle)"},"content":{"rendered":"

Sizing a spare tire cover is one of those tasks that feels harder than it is, mostly because the obvious first instinct is wrong. Buyers see “17” on the wheel and assume they need a 17-inch cover. Then the 17-inch cover arrives, slides over the lug nuts, and stops cold — because the actual tire is 32 inches across, not 17.<\/p>\n

The cover wraps the entire tire, from one edge of the tread across the face to the other edge. That number is always bigger than the rim size, sometimes by a lot. Once you understand that, sizing becomes mechanical: read a code on the sidewall, do a small calculation, and you have your answer. Or pull out a tape measure and skip the math entirely.<\/p>\n

There are three ways to get to the right size, and any of them works. Use the one that fits what you have access to — the spare in front of you, the tire code on the sidewall, or just the make and model of the vehicle.<\/p>\n

Here is the full guide.<\/p>\n

Spare tire cover size equals overall tire diameter, not rim size. Use a tape measure across the tire face (edge to edge through the center), or read the size code on the sidewall (for example, LT255\/75R17 → 32″ cover) and look it up in the chart below. We make every size from 14″ to 37″ and beyond, with custom sizing always free.<\/strong><\/p>\n

Method 1 — Read the sidewall (the fastest way)<\/h2>\n

Every tire has its size molded into the sidewall. Look for a code like:<\/p>\n

LT255\/75R17 121\/118Q<\/pre>\n
The first number (255) is section width in millimeters. The second (75) is aspect ratio — sidewall height as a percentage of width. The R is for radial. The 17 is rim diameter in inches.<\/p>\n
To get overall tire diameter:<\/p>\n
diameter = rim_inches + 2 × (width_mm × aspect_ratio \/ 100) \/ 25.4<\/pre>\n
For LT255\/75R17: 17 + 2 × (255 × 0.75 \/ 25.4) = 17 + 15.05 = 32.05 inches → 32″ cover.<\/strong><\/p>\n
Or just use the reference table below — we have already done the math for the most common sizes.<\/p>\n
Method 2 — Tape measure across the tire<\/h2>\n
If you cannot read the sidewall (mud, faded code, vintage tire), measure directly:<\/p>\n
    \n
  1. Have the spare upright on a flat surface — tailgate-mounted, hitch-mounted, or set on the ground.<\/li>\n
  2. Place a tape measure across the front face of the tire, from edge of tread to edge of tread, passing through the dead-center of the wheel.<\/li>\n
  3. Read the number in inches. That is your cover size.<\/li>\n<\/ol>\n
    If your measurement falls between two cover sizes (32.5″, for instance), round up<\/strong> to the next size. A slightly oversized cover is easy to tighten with the drawcord; an undersized cover will not seat properly.<\/p>\n
    Method 3 — Look up your stock vehicle size<\/h2>\n
    If your spare is the factory tire, every common vehicle has a known cover size:<\/p>\n
    Jeep<\/h3>\n