125/70R15 Tire Size in Inches and Millimeters
125/70R15 tires have a diameter of 21.9" (557 mm), a tread width of 4.9" (125 mm), and a wheel diameter of 15" (381 mm).The sidewall of the tire is 3.5" (88 mm), and the tire's circumference is 68.8" (1749 mm). This means a 125/70R15 tire will make make 921 revolutions per mile, or 572 revolutions per kilometer.



Spec | Inches | Metric |
---|---|---|
Diameter | 21.9" | 557 mm |
Width | 4.9" | 125 mm |
Wheel | 15" | 381 mm |
Sidewall | 3.5" | 88 mm |
Circum | 68.8" | 1749 mm |
Revolutions | 921 per mile | 572 per km |
What Does 125/70R15 Mean?
The tire size 125/70R15 is a common size used on many trucks, SUVs, and other larger vehicles.
Here is what each part of the size designation represents:
- 125: This number represents the width of the tire in millimeters. In this case, the tire is 125 millimeters wide.
- 70: 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 70% 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 125/70R15 Into Inches
The 125/70R15 conversion is fairly simple. The first number in the tire size, 125, represents the width of the tire in millimeters. To convert this to inches, we divide 125 by 25.4 (since there are 25.4 millimeters in an inch). This gives us approximately 4.9 inches.
The second number in the tire size, 70, represents the aspect ratio or the height of the tire as a percentage of its width. To calculate the height in inches, we multiply 4.9 by 0.70, which gives us approximately 3.5 inches.
Finally, the last number in the tire size, 15, represents the diameter of the wheel rim in inches. Therefore, the tire size 125/70R15 can be expressed in inches as roughly 4.9 inches wide, 3.5 inches tall, and designed to fit a 15-inch wheel rim.
Frequently Asked Questions About 125/70R15 Tires
How tall is a 125/70R15 tire?
A 125/70R15 tire has an approximate height, also known as the overall diameter, of 21.9 inches (557 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 125/70R15 tire?
A 125/70R15 tire has a width of approximately 4.9 inches (125 millimeters). The width of the tire is the first number in the tire size designation, which in this case is “125”. 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 125/70R15 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 |
---|---|---|---|
115/70R15 | 21.4" | 543 mm | 15 mm |
115/70R16 | 22.4" | 568 mm | 16 mm |
125/70R15 | 21.9" | 557 mm | 15 mm |
135/60R16 | 22.4" | 568 mm | 16 mm |
135/70R15 | 22.5" | 571 mm | 15 mm |
135/80R13 | 21.5" | 546 mm | 13 mm |
135/80R14 | 22.5" | 572 mm | 14 mm |
145/65R14 | 21.4" | 544 mm | 14 mm |
145/65R15 | 22.4" | 569 mm | 15 mm |
145/80R13 | 22.1" | 562 mm | 13 mm |
155/60R15 | 22.3" | 567 mm | 15 mm |
155/65R14 | 22" | 558 mm | 14 mm |
155/70R13 | 21.6" | 548 mm | 13 mm |
155/80R12 | 21.8" | 553 mm | 12 mm |
165/40R17 | 22.2" | 564 mm | 17 mm |
165/45R16 | 21.8" | 554 mm | 16 mm |
165/50R15 | 21.5" | 547 mm | 15 mm |
165/50R16 | 22.5" | 572 mm | 16 mm |
165/55R15 | 22.2" | 563 mm | 15 mm |
165/60R14 | 21.8" | 554 mm | 14 mm |
165/65R13 | 21.4" | 544 mm | 13 mm |
165/65R14 | 22.4" | 570 mm | 14 mm |
165/70R13 | 22.1" | 562 mm | 13 mm |
175/50R15 | 21.9" | 557 mm | 15 mm |
175/55R15 | 22.6" | 573 mm | 15 mm |
175/60R14 | 22.3" | 566 mm | 14 mm |
175/65R13 | 22" | 558 mm | 13 mm |
185/45R15 | 21.5" | 547 mm | 15 mm |
185/50R14 | 21.3" | 542 mm | 14 mm |
185/50R15 | 22.3" | 567 mm | 15 mm |
185/55R14 | 22" | 560 mm | 14 mm |
185/60R13 | 21.7" | 552 mm | 13 mm |
185/65R13 | 22.4" | 570 mm | 13 mm |
195/40R16 | 22.1" | 562 mm | 16 mm |
195/45R15 | 21.9" | 557 mm | 15 mm |
195/55R13 | 21.4" | 544 mm | 13 mm |
195/55R14 | 22.4" | 570 mm | 14 mm |
195/60R13 | 22.2" | 564 mm | 13 mm |
205/40R16 | 22.4" | 570 mm | 16 mm |
205/45R15 | 22.2" | 565 mm | 15 mm |
205/50R14 | 22.1" | 562 mm | 14 mm |
215/35R16 | 21.9" | 556 mm | 16 mm |
215/40R15 | 21.8" | 553 mm | 15 mm |
215/50R13 | 21.5" | 546 mm | 13 mm |
225/45R14 | 22" | 558 mm | 14 mm |
225/50R13 | 21.9" | 556 mm | 13 mm |
235/50R13 | 22.3" | 566 mm | 13 mm |
245/35R15 | 21.8" | 553 mm | 15 mm |
275/35R15 | 22.6" | 573 mm | 15 mm |