The 255/50R20 tire size measures about 10.04 inches wide and 30.04 inches tall, with a 5.02-inch sidewall. It mounts on a 20-inch wheel and is common on SUVs, crossovers and performance vehicles in the USA.
This guide covers the exact 255/50R20 dimensions, the vehicles that use these tires and how they compare with nearby sizes. It also explains how to pick the right 255/50R20 tires without wasting money.
What Does 255/50R20 Mean?
Every number in a tire size code has a job. Once you know them, any tire sidewall becomes easy to read.
- 255 is the section width in millimeters. It is measured from one sidewall to the other.
- 50 is the aspect ratio. The sidewall height equals 50% of the width.
- R means radial construction. Almost all modern car and SUV tires are radial.
- 20 is the wheel diameter in inches.
So the sidewall is 255 × 0.50 = 127.5 mm. That is the same as 5.02 inches.
Load Index and Speed Rating
A 109 load index means each tire carries up to 2,271 pounds. A 105 carries 2,039 pounds. Many 255/50R20 tires are XL (extra load). Some are SL (standard load).
Speed ratings add one more detail:
- H is up to 130 mph.
- V is up to 149 mph.
- W is up to 168 mph.
- Y is up to 186 mph.
Never go below the load index and speed rating on your vehicle’s door-jamb tire placard.
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255/50R20 Tire Size in Inches
| Specification | Inches | Millimeters | Centimeters |
|---|---|---|---|
| Section width | 10.04 in | 255 mm | 25.5 cm |
| Sidewall height | 5.02 in | 127.5 mm | 12.75 cm |
| Overall diameter | 30.04 in | 763 mm | 76.3 cm |
| Circumference | 94.3 in | 2,395 mm | 239.5 cm |
| Revolutions per mile | 672 | 418 per km | 418 per km |
| Approved rim width | 7 to 9 in | 178 to 229 mm | 17.8 to 22.9 cm |
Specs vary slightly by brand. Always check the maker’s data for the exact tire you buy.
How to Convert 255/50R20 From Millimeters to Inches
Use these simple steps:
- Width: 255 ÷ 25.4 = 10.04 in
- Sidewall: 127.5 ÷ 25.4 = 5.02 in
- Diameter: 20 + (2 × 5.02) = 30.04 in
- Circumference: 3.14 × 30.04 ≈ 94.3 in
- Revs per mile: 63,360 ÷ 94.3 ≈ 672
The 63,360 is the number of inches in one mile. The same method works for any metric tire size.
255/50R20 vs 255/45R20 and 255/55R20
These three sizes share the same width and wheel diameter. Only the sidewall height changes.
| Tire Size | Section Width | Sidewall Height | Overall Diameter | Circumference | Revolutions per Mile |
|---|---|---|---|---|---|
| 255/45R20 | 10.04 in | 4.52 in | 29.04 in | 91.2 in | 695 |
| 255/50R20 | 10.04 in | 5.02 in | 30.04 in | 94.3 in | 672 |
| 255/55R20 | 10.04 in | 5.52 in | 31.04 in | 97.5 in | 650 |
Each step changes the overall diameter by about 1 inch. That is roughly 3.3%.
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Speedometer Error and the 3% Rule
Tire height changes speedometer and odometer accuracy. A common guide says to stay within about 3% of the original diameter.
Here is a real example. Your speedometer reads 60 mph on a 255/50R20. On a 255/55R20, your true speed is about 62 mph. On a 255/45R20, it is about 58 mph.
A taller or shorter tire can also affect ABS, traction control and gearing. A taller tire may rub the wheel well too.
Which Size Should You Choose?
Match the size on your tire placard first. That is the factory-approved choice.
- A lower sidewall (255/45R20) gives sharper steering. It also gives a firmer ride.
- A taller sidewall (255/55R20) gives more cushion. It also helps protect the wheel from potholes.
If you want to change sizes, ask a tire shop to confirm clearance and load rating first.
Vehicles That Use 255/50R20 Tires
Models often listed with this size include:
- BMW X5 and BMW X6
- Audi Q7
- Porsche Cayenne
- Mercedes-Benz GLE-Class
- Land Rover Range Rover Sport
- Ford Edge
Fitment depends on the model year, trim and wheel option. Two trims of the same SUV can use different tire sizes. Check the driver-door placard or your owner’s manual before you buy.
Wheel Width and Plus-Sizing Checks
This tire is approved for 7 to 9 inch wide wheels. A wheel outside that range can strain the bead and hurt handling. Some owners move from 18-inch or 19-inch wheels up to 20-inch wheels.
This is called plus-sizing. To keep the overall diameter close to stock, choose a tire with a shorter sidewall.
Also confirm:
- Wheel offset and bolt pattern
- Brake caliper clearance
- Load index that meets or beats the original
- TPMS sensor compatibility
Since the 2007 model year, TPMS has been required on new US passenger vehicles. The shop should reset or reprogram the sensors after install.
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Best 255/50R20 Tires by Type and Price
There is no single best tire. The best 255/50R20 tire depends on your climate and driving style.
Best 255/50R20 Tires by Driving Need
- All-season: Pirelli Scorpion All Season Plus 3 and Michelin CrossClimate 2 offer balanced grip and tread life.
- All-weather: Goodyear Assurance WeatherReady carries the 3PMSF (three-peak mountain snowflake) symbol for snow use.
- All-terrain: Falken Wildpeak A/T Trail and Nitto Terra Grappler G3 suit gravel and light trails.
- Performance: Bridgestone Potenza Sport A/S and Pirelli P Zero favor sharp cornering and wet braking.
- Winter: Bridgestone Blizzak and Michelin X-Ice Snow SUV are built for ice and deep cold.
Model lineups change, so confirm the size is still offered before you shop.
255/50R20 Tire Price Range in the USA
Online listings for this size typically run from about $150 to $475 per tire. Budget all-season models sit at the low end. Ultra-high-performance and winter models cost more.
Remember the extra costs. Mounting, balancing, valve stems and disposal fees can add to a set of four.
255/50R20 Tire Buying Checklist
Before you pay, check these points:
- Size match with your door-jamb placard
- Load index and speed rating
- Treadwear warranty and UTQG rating (treadwear, traction and temperature)
- DOT date code, a four-digit week and year stamp. Many carmakers advise replacing tires at six years, even with tread left.
- Tread depth: most US states set the legal minimum at 2/32 inch.
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FAQ’s About 255/50R20 Tire Size
What is the size of a 255/50R20 tire in inches?
A 255/50R20 tire is about 10.04 inches wide and 30.04 inches tall. Its sidewall is about 5.02 inches. It fits a 20-inch wheel.
What vehicles use 255/50R20 tires?
This size is often listed for the BMW X5, BMW X6, Audi Q7, Porsche Cayenne, Mercedes-Benz GLE, Range Rover Sport and Ford Edge. Fitment changes by trim and year, so check your tire placard.
What wheel width fits a 255/50R20 tire?
Most 255/50R20 tires are approved for 7 to 9 inch wide wheels. Check the specific tire’s approved range before you mount it.
Can I replace 255/45R20 or 255/55R20 with 255/50R20?
Sometimes, but not always. The diameter changes by about 1 inch, or 3.3%. That shifts speedometer accuracy and may affect clearance. Confirm with a tire shop first.
What are the best 255/50R20 tires for all-season and winter use?
For all-season driving, popular picks include the Pirelli Scorpion All Season Plus 3 and Michelin CrossClimate 2. For winter, look at the Bridgestone Blizzak line or the Michelin X-Ice Snow SUV. Choose tires with the 3PMSF symbol for true snow use.
How much do 255/50R20 tires cost in the USA?
Expect roughly $150 to $475 per tire. Price depends on brand, tire type and warranty. Add installation costs on top.
I’m Richard Hayes, a content researcher and writer at TireMeasurements.com, specializing in measurements, tire measurements, tire sizing, wheel fitment, and related automotive topics.
