225/55R15 Tire Size in Inches and Millimeters
225/55R15 tires have a diameter of 24.8" (629 mm), a tread width of 8.9" (225 mm), and a wheel diameter of 15" (381 mm).The sidewall of the tire is 4.9" (124 mm), and the tire's circumference is 77.9" (1975.1 mm). This means a 225/55R15 tire will make make 813 revolutions per mile, or 506 revolutions per kilometer.



Spec | Inches | Metric |
---|---|---|
Diameter | 24.8" | 629 mm |
Width | 8.9" | 225 mm |
Wheel | 15" | 381 mm |
Sidewall | 4.9" | 124 mm |
Circum | 77.9" | 1975.1 mm |
Revolutions | 813 per mile | 506 per km |
What Does 225/55R15 Mean?
The tire size 225/55R15 is a common size used on many trucks, SUVs, and other larger vehicles.
Here is what each part of the size designation represents:
- 225: This number represents the width of the tire in millimeters. In this case, the tire is 225 millimeters wide.
- 55: This number represents the aspect ratio of the tire, which is the height of the tire's sidewall as a percentage of its width. In this case, the sidewall height is 55% of the tire's width.
- R: This letter indicates the tire's construction type. “R” stands for radial construction, which is the most common type of tire construction today.
- 15: This number represents the diameter of the wheel that the tire is designed to fit on, in inches. In this case, the tire is designed to fit on a 15-inch wheel.

How To Convert 225/55R15 Into Inches
The 225/55R15 conversion is fairly simple. The first number in the tire size, 225, represents the width of the tire in millimeters. To convert this to inches, we divide 225 by 25.4 (since there are 25.4 millimeters in an inch). This gives us approximately 8.9 inches.
The second number in the tire size, 55, represents the aspect ratio or the height of the tire as a percentage of its width. To calculate the height in inches, we multiply 8.9 by 0.55, which gives us approximately 4.9 inches.
Finally, the last number in the tire size, 15, represents the diameter of the wheel rim in inches. Therefore, the tire size 225/55R15 can be expressed in inches as roughly 8.9 inches wide, 4.9 inches tall, and designed to fit a 15-inch wheel rim.
Frequently Asked Questions About 225/55R15 Tires
How tall is a 225/55R15 tire?
A 225/55R15 tire has an approximate height, also known as the overall diameter, of 24.8 inches (629 mm). This height can vary slightly depending on the brand and model of the tire, as well as the amount of air pressure in the tire.How wide is a 225/55R15 tire?
A 225/55R15 tire has a width of approximately 8.9 inches (225 millimeters). The width of the tire is the first number in the tire size designation, which in this case is “225”. It’s important to note that the actual width of the tire may vary slightly depending on the brand and model of the tire, and the width may also be affected by the amount of air pressure in the tire.Understanding Tire Speed Ratings
When choosing the right tires for your vehicle, understanding the speed rating is crucial. But what exactly is a speed rating, and why does it matter?What is a Tire Speed Rating?
A tire's speed rating indicates the maximum speed a tire can safely sustain over time. It's a manufacturer's assurance of tire performance, marked by a letter on the tire's sidewall. This rating is determined under controlled laboratory conditions and is part of a broader standard established by industry entities like the European Tyre and Rim Technical Organisation (ETRTO) and the U.S. Department of Transportation.Common Speed Ratings Explained
- P-Rated: Up to 94 mph - Suitable for smaller sedans or light-duty vehicles.
- Q-Rated: Up to 100 mph - Often found on SUVs and light trucks with consistent highway use.
- R-Rated: Up to 106 mph - Typically for medium-duty trucks and vans.
- S-Rated: Up to 112 mph - Common for family sedans and larger vehicles with moderate performance.
- T-Rated: Up to 118 mph - Optimal for family vehicles, including minivans and some coupes.
Why is the Speed Rating Important?
The speed rating is not just about how fast you can legally drive; it's about safety and performance:- Ensures Safety: It guarantees that the tire can handle certain speeds without overheating and failing, which can prevent blowouts.
- Optimizes Performance: Higher ratings often indicate better handling characteristics, important for maintaining vehicle stability.
- Legal and Insurance Considerations: Matching the speed rating suggested by your vehicle manufacturer can be essential for insurance and warranty purposes.
Alternate 225/55R15 Replacement Tire Sizes
Upsizing your wheels or tires? Replacement tires must be within 3% of the diametor of the original tire. The following sizes fall within that range - click on any size to see detailed info about that tire and wheel combination.
Size | Diameter | Width | Wheel |
---|---|---|---|
115/70R19 | 25.4" | 645 mm | 19 mm |
125/70R18 | 24.9" | 633 mm | 18 mm |
125/80R17 | 24.9" | 632 mm | 17 mm |
125/85R16 | 24.3" | 618 mm | 16 mm |
125/90R16 | 24.9" | 632 mm | 16 mm |
135/60R18 | 24.4" | 619 mm | 18 mm |
135/60R19 | 25.4" | 645 mm | 19 mm |
135/70R17 | 24.5" | 622 mm | 17 mm |
135/70R18 | 25.5" | 647 mm | 18 mm |
135/80R16 | 24.5" | 622 mm | 16 mm |
135/90R15 | 24.6" | 625 mm | 15 mm |
145/65R18 | 25.4" | 645 mm | 18 mm |
145/70R17 | 25" | 636 mm | 17 mm |
145/80R16 | 25.1" | 638 mm | 16 mm |
155/60R18 | 25.3" | 643 mm | 18 mm |
155/80R15 | 24.8" | 629 mm | 15 mm |
165/80R14 | 24.4" | 620 mm | 14 mm |
165/80R15 | 25.4" | 645 mm | 15 mm |
175/45R18 | 24.2" | 615 mm | 18 mm |
175/55R17 | 24.6" | 624 mm | 17 mm |
175/60R16 | 24.3" | 616 mm | 16 mm |
175/70R15 | 24.7" | 627 mm | 15 mm |
175/75R14 | 24.3" | 618 mm | 14 mm |
175/75R15 | 25.3" | 643 mm | 15 mm |
175/80R14 | 25" | 636 mm | 14 mm |
185/50R17 | 24.3" | 618 mm | 17 mm |
185/60R16 | 24.7" | 628 mm | 16 mm |
185/65R15 | 24.4" | 621 mm | 15 mm |
185/65R16 | 25.4" | 646 mm | 16 mm |
185/70R14 | 24.3" | 616 mm | 14 mm |
185/70R15 | 25.2" | 641 mm | 15 mm |
185/75R14 | 25" | 634 mm | 14 mm |
185/80R13 | 24.6" | 626 mm | 13 mm |
195/50R17 | 24.7" | 628 mm | 17 mm |
195/55R16 | 24.4" | 620 mm | 16 mm |
195/55R17 | 25.4" | 646 mm | 17 mm |
195/60R15 | 24.2" | 615 mm | 15 mm |
195/60R16 | 25.2" | 640 mm | 16 mm |
195/65R15 | 25" | 635 mm | 15 mm |
195/70R14 | 24.8" | 630 mm | 14 mm |
205/40R18 | 24.4" | 621 mm | 18 mm |
205/45R17 | 24.3" | 616 mm | 17 mm |
205/45R18 | 25.2" | 641 mm | 18 mm |
205/50R16 | 24.1" | 612 mm | 16 mm |
205/50R17 | 25.1" | 638 mm | 17 mm |
205/55R16 | 24.9" | 632 mm | 16 mm |
205/60R15 | 24.7" | 627 mm | 15 mm |
205/65R14 | 24.5" | 622 mm | 14 mm |
205/65R15 | 25.5" | 647 mm | 15 mm |
205/70R13 | 24.3" | 618 mm | 13 mm |
205/70R14 | 25.4" | 644 mm | 14 mm |
215/30R20 | 25.1" | 638 mm | 20 mm |
215/35R19 | 24.9" | 633 mm | 19 mm |
215/40R18 | 24.8" | 629 mm | 18 mm |
215/45R17 | 24.6" | 626 mm | 17 mm |
215/50R16 | 24.5" | 622 mm | 16 mm |
215/55R15 | 24.3" | 617 mm | 15 mm |
215/55R16 | 25.3" | 642 mm | 16 mm |
215/60R14 | 24.2" | 614 mm | 14 mm |
215/60R15 | 25.2" | 639 mm | 15 mm |
215/65R14 | 25" | 636 mm | 14 mm |
225/30R19 | 24.4" | 619 mm | 19 mm |
225/30R20 | 25.4" | 644 mm | 20 mm |
225/35R18 | 24.2" | 615 mm | 18 mm |
225/35R19 | 25.2" | 641 mm | 19 mm |
225/40R17 | 24.1" | 612 mm | 17 mm |
225/40R18 | 25.1" | 637 mm | 18 mm |
225/45R17 | 25" | 634 mm | 17 mm |
225/50R16 | 24.9" | 632 mm | 16 mm |
225/55R15 | 24.8" | 629 mm | 15 mm |
225/60R14 | 24.6" | 626 mm | 14 mm |
235/30R19 | 24.6" | 625 mm | 19 mm |
235/35R18 | 24.4" | 621 mm | 18 mm |
235/35R19 | 25.5" | 647 mm | 19 mm |
235/40R17 | 24.4" | 620 mm | 17 mm |
235/40R18 | 25.4" | 645 mm | 18 mm |
235/45R17 | 25.4" | 644 mm | 17 mm |
235/50R15 | 24.3" | 617 mm | 15 mm |
235/50R16 | 25.3" | 642 mm | 16 mm |
235/55R15 | 25.2" | 639 mm | 15 mm |
235/60R13 | 24.1" | 612 mm | 13 mm |
235/60R14 | 25.1" | 638 mm | 14 mm |
245/30R19 | 24.8" | 631 mm | 19 mm |
245/35R18 | 24.8" | 629 mm | 18 mm |
245/40R17 | 24.7" | 628 mm | 17 mm |
245/45R16 | 24.6" | 626 mm | 16 mm |
245/50R15 | 24.7" | 627 mm | 15 mm |
255/30R18 | 24.1" | 611 mm | 18 mm |
255/30R19 | 25.1" | 637 mm | 19 mm |
255/35R18 | 25" | 635 mm | 18 mm |
255/40R17 | 25" | 636 mm | 17 mm |
255/45R15 | 24.1" | 611 mm | 15 mm |
255/55R14 | 25" | 636 mm | 14 mm |
265/30R18 | 24.3" | 617 mm | 18 mm |
265/30R19 | 25.3" | 643 mm | 19 mm |
265/35R17 | 24.3" | 618 mm | 17 mm |
265/35R18 | 25.3" | 643 mm | 18 mm |
265/40R17 | 25.4" | 644 mm | 17 mm |
265/45R16 | 25.4" | 644 mm | 16 mm |
265/50R14 | 24.5" | 622 mm | 14 mm |
265/50R15 | 25.5" | 647 mm | 15 mm |
275/25R20 | 25.4" | 646 mm | 20 mm |
275/35R17 | 24.6" | 624 mm | 17 mm |
285/30R18 | 24.8" | 629 mm | 18 mm |
285/35R17 | 24.9" | 632 mm | 17 mm |
295/25R19 | 24.8" | 631 mm | 19 mm |
295/30R18 | 25" | 635 mm | 18 mm |
295/35R17 | 25.1" | 638 mm | 17 mm |
305/25R19 | 25" | 635 mm | 19 mm |
305/30R18 | 25.2" | 641 mm | 18 mm |
305/35R17 | 25.4" | 646 mm | 17 mm |
315/25R19 | 25.2" | 641 mm | 19 mm |
315/30R18 | 25.5" | 647 mm | 18 mm |
345/35R15 | 24.5" | 623 mm | 15 mm |