What Does 245/50R20 Mean? | Tire Size Decoded

245/50R20 is a tire size code: 245 millimeters wide, 50 percent aspect ratio, radial construction, and a 20-inch wheel diameter.

So here’s what 245/50R20 means in practice — four separate measurements packed into one code: metric width, a percentage ratio, a construction type, and an imperial wheel size. Reading each one correctly is the difference between a tire that fits and one that doesn’t, whether you’re buying replacements or checking a used car before a test drive.

Breaking Down The 245/50R20 Size Code

Every tire size code carries four pieces of information: section width, aspect ratio, construction type, and wheel diameter. Each part controls a different fitment detail, and the full code is printed in large lettering on every tire’s sidewall.

245 — section width in millimeters. This is the tire’s width measured from the widest point of one sidewall to the widest point of the other, once mounted on its specified rim. It’s a metric measurement, which is why 245 translates to about 9.6 inches.

50 — aspect ratio. The sidewall height is 50 percent of the section width, so the sidewall runs about 122.5 mm, or just under 4.8 inches, from the rim to the tread. A lower number here means a shorter, stiffer sidewall and a firmer ride.

R — radial construction. The belt plies run radially, straight across the tire, which is the standard design for modern passenger tires. Older bias-ply tires carry a D in this position instead.

20 — wheel diameter in inches. The tire is built for a 20-inch rim, and that match must be exact.

How Big Is A 245/50R20 Tire In Inches?

Tire makers publish these derived figures for every size they offer — Pirelli’s 245/50R20 tire catalog lists the full spec sheet for this size. The overall diameter is the wheel plus two sidewall heights: 20 inches plus 4.8 inches on each side equals 29.6 inches.

One detail shoppers often miss: load index and speed rating sit outside the base size code.

If you’re ready to buy, our picks for the best 245/50R20 tires compare the top performers in this size side by side.

Common 245/50R20 Mistakes To Avoid

Four mistakes cause most fitment problems with this size, and Rochester Mazda’s tire-size explainer flags the same ones. The traps:

• Reading the 20 as the tire’s overall height. It’s the wheel diameter in inches; the tire itself stands about 29.6 inches tall.
• Treating 245 as inches. It’s 245 millimeters, or about 9.6 inches — a 245-inch tire would be over 20 feet wide.
• Skipping the load index and speed rating. The base code doesn’t include them; read the full marking such as 102V before buying.
• Matching only the size code. Vehicle manufacturer fitment and rim width requirements still apply, even when the code looks identical.

FAQs

Will a 245/50R20 tire fit any 20-inch wheel?

No. The 20 identifies the wheel diameter, but rim width must be compatible as well. This size is commonly mounted on rims 7.0 to 8.5 inches wide, and the vehicle’s own fitment requirements also apply. Always confirm both the tire size code and the rim width against the manufacturer’s spec before mounting.

What does the V in P245/50R20 102V mean?

Both sit outside the base 245/50R20 code and must match the vehicle’s requirements.

What’s the difference between 245/50R20 and 245/45R20?

The aspect ratio changes: 45 means the sidewall is 45 percent of the width instead of 50 percent, making it about half an inch shorter. Stick with the size the vehicle specifies.