# Tire Size 285 FAQ

To help you navigate the confusion, we have compiled a Tire Size 285 FAQ that answers some of the most common questions about this tire size. Whether you are looking to replace your old tires or simply want to upgrade, this guide will give you the information you need to make an informed decision.

**What Does 215 Mean On A Tire?**

The “215” on a tire refers to the width of the tire in millimeters. This number is part of a series of numbers and letters that make up the tire size code, which provides information about the tire’s dimensions, load capacity, and speed rating.

In this case, a tire with “215” printed on its sidewall has a width of 215 millimeters (or approximately 8.46 inches) from one side to the other when measured at the widest point of the tire. This width is also known as the section width or cross-section width.

**How Tall Are 285 Tires?**

To determine the overall height of a tire with a size of 285, you’ll need to know the aspect ratio and the wheel diameter as well. The tire size is usually written in the format of 285/XX/RYY, where:

- 285 is the section width of the tire in millimeters.
- XX is the aspect ratio, which is the ratio of the tire’s Height (or sidewall height) to its width, expressed as a percentage.
- R represents that the tire is of radial construction.
- YY is the wheel diameter in inches.

The overall height can be calculated using this formula: Overall Diameter = (2 x (Sidewall Height)) + Wheel Diameter.

To find the sidewall height, use the aspect ratio and section width: Sidewall Height = (Section Width x Aspect Ratio) / 100

For example, if you have a tire size of 285/45/R20: Sidewall Height = (285 x 45) / 100 = 128.25 mm

Convert the sidewall height to inches (since the wheel diameter is given in inches): Sidewall Height in inches = 128.25 mm / 25.4 = 5.05 inches.

Now, use the overall diameter formula: Overall height= (2 x 5.05) + 20 = 30.1 inches

The tire’s overall height would be approximately 30.1 inches in this example. Please note that this is an approximate value, as actual tire dimensions can vary slightly depending on the manufacturer and specific tire model.

**How Wide Are 285 Tires?**

The “285” in a tire size refers to the width of the tire, measured in millimeters. A tire with a width of 285 millimeters is approximately 11.22 inches wide. This width, also known as the section width or cross-section width, is the distance from one sidewall to the other, measured at the tire’s widest point. Remember that actual tire dimensions may vary slightly depending on the manufacturer and specific tire model.

**Are 285 Tires The Same As 33?**

Yes, 285 tires are essentially the same as 33-inch tires. While minor differences are due to different measurement systems, they are largely similar in size. “285” represents the tread width in millimeters, while “33” denotes the tire’s diameter in inches.

To demonstrate the relationship between 285 and 33-inch tires, consider the following example using a 285/70/17 tire:

- Measure the exact sidewall height: Multiply the tread width (285 mm) by the sidewall height (70%) to get 199.5 mm. Since a tire has two sidewalls, multiply 199.5 mm by 2 for a total sidewall height of 399 mm.
- Convert the rim diameter to metric: Convert the 17-inch rim diameter to millimeters by multiplying it by 25.4, resulting in 431.8 millimeters.
- Calculate the overall tire diameter: Add the total sidewall height (399 mm) and the rim diameter (431.8 mm) to get 830.8 mm.

To find the tire diameter in inches, divide the total diameter (830.8 mm) by 25.4. This results in approximately 32.7 inches, which is close to 33 inches. Therefore, a 285 tire is roughly equivalent to a 33-inch tire in size.

**Can I Put 275 Tires On 285 Rims?**

Yes, it is possible to replace 275-width tires with 285-width tires. However, before changing your vehicle’s tire size, consult the doorjamb or owner’s manual to ensure the new size is compatible with your vehicle’s specifications and performance requirements.

A 275/65R18 sized tire has a rim width mounting range of 7.5-9.5″, while the 285/70R17 sized tire has a rim width mounting range of 8.5-10.5″. As you can observe, there is an overlap between the 275 and 285 tire size rim width ranges. This indicates that using a 275-width tire on a rim designed for a 285-width tire may be feasible, or vice versa.

However, always consult with a professional tire specialist or refer to the manufacturer’s guidelines before making changes to your tire and rim setup to ensure safety and optimal performance.