Understanding what size tires you need can be difficult. The numbers on the wall are not all a consistent size; some are in millimeters, while others are in inches. In addition, the size of your car, truck, or trailer that is ideal for your needs may vary depending on where you live.
In today’s guide, we’re going to cover the various tire sizes for different vehicles. We’ll also go over the hieroglyphics on the side wall of a tire to help you understand what they mean.
Tire vs. Wheel vs. Rim
First and foremost, let’s go over the über basics: what í a tire, a wheel, and a rim? You’ll need to know what all 3 of these things are if you want to understand tire sizes.
The tire is fastened to the outer edge of the wheel by means of the rim, which also acts as a sort of reinforcement. If you drive between 12,000 and 15,000 miles per year, you’ll need to replace the tire once every 3 to 5 years.
Many different parts come together to form the wheel. The lug nuts hold the wheel to the axle via the hub, which is the disc at the center of the wheel. For all intents and purposes, a wheel includes everything minus the tire.
Finally, you can think of the rim as one part of the wheel. The rim is mounted on the outer edge and acts as a sort of reinforcement to fasten the tire to the wheel.
With the basics out of the way, we can jump straight into the crux of the matter.
Car Tire Sizes
From the Goodyear website, the most common car tire sizes are as follows:
- 14 in.
- 15 in.
- 16 in.
- 17 in.
- 18 in.
- 19 in.
- 20 in.
- 21 in.
- 22 in.
This doesn’t limit the possibility that car tires can measure 24 inches and beyond, especially when you take into account the various large-sized vehicles (monster trucks, for instance) that sit atop massive rubber tires. In addition, you can also find 13-inch tires for smaller vehicles, such as the Renault KWID and the Maruti Celerio.
How to Read Car Tire Sizes
Now that we know what the most common (and a few uncommon) car tire sizes are, we have to ask ourselves: what does X inches refer to?
In simple terms, the size of a tire refers to what rim size it fits. For instance, 15-inch tires fit snugly around 15-inch rims. However, this doesn’t tell the whole story.
If you take a look at the outer wall of your tires right now, you’ll most likely find a jumble of letters, numbers, and symbols—i.e.2, 225/65-R17. Here’s how you understand these mysterious codes.
- Width—The distance from one side wall to the opposite side wall) in millimeters. In this example’s case, the width is 225 millimeters.
- Aspect Ratio—The ratio between the height of the tire’s side walls (edge of the rim to tread) and the tire’s width (225 millimeters in this example) expressed in percentages.
- Construction—The code that denotes what type of tire it is. The R in this example shows that the tire is a radial tire, which means the tire was made with beaded cords that are perpendicular to the travel direction. Other codes include B (bias belt) and D (diagonal).
There may also be other codes that appear on your car’s tires. Just for fun, let’s go over them real fast.
- Rim diameter—This is pretty straightforward; it refers to the diameter of the width. In other words, it describes what size rim fits in the tire. In this example, the 17 shows that the tire is designed to fit around a 17-inch rim.
- Service type—The code right before the width (e.g., 225). It determines what sort of vehicle the tire is for. In the case of cars, the code will be P (passenger vehicles, SUVs, light-duty pickups).
- Load index—This refers to how much mass the tire can support when inflated properly. Most passenger cars will have a load index of between 75 and 105.
- Speed rating—The maximum speed in which the tire moves your vehicle while also dissipating heat. For instance, if a tire has a speed rating of 91, any speed over 91 MPH will cause heat damage to the tire.
Car Tire Sizes in Inches
Above, I explained how you can read the size of a tire, which includes codes expressed in millimeters (width) and inches (rim diameter). But what if you want to measure the size of a tire in inches?
Well, there’s a code for that, too, though it’s a bit different. Let’s use the previous car tire size—225/65-R17—for this example. Its equivalent in inches would be 28.5X8.9R17. The code is a bit different, so let’s break it down.
- Overall tire diameter—This refers to the distance between the treads on opposite ends of the tire. In other words, it’s the farthest distance between 2 tread points on the tire. In this tire size example, the tire diameter is 28.5 inches.
- Width—Again, the distance between one side of the side wall to the opposite side. The 225-millimeter rating earlier would equal roughly 8.9 inches.
The final two codes (R and 17) are the same—radial tire that fits around 17-inch rims.
Car Tire Size Chart
There’s quite a lot to unpack here, so you might want to prepare a cup of coffee for the adventure we’re going on. Below, I’m going to explain the most common tire size codes for tires from 14 to 18 inches.
14 inches
| Tire Size | Compatible Tire Sizes |
| 14 in. | 115/70-14
135-14 135/80-14 165-14 165/65-14 175-14 175/65-14 175/70-14 185-14 185/55-14 185/60-14 185/65-14 185/70-14 185/75-14 195-14 195/60-14 195/70-14 195/75-14 205/55-14 205/70-14 205/75-14 215/60-14 215/70-14 215/75-14 225/50-14 225/60-14 225/70-14 235/60-14 245/60-14 |
15 inches
| Tire Size | Compatible Tire Sizes |
| 15 in. | 115/70-15
125/70-15 125/80-15 145/65-15 155-15 155/60-15 155/80-15 165-15 165/60-15 165/65-15 175/55-15 175/60-15 175/65-15 175/70-15 185-15 185/55-15 185/60-15 185/65-15 185/70-15 195/45-15 195/50-15 195/55-15 195/60-15 195/65-15 195/70-15 205/50-15 205/55-15 205/60-15 205/65-15 205/70-15 205/75-15 215/50-15 215/60-15 215/65-15 215/70-15 215/75-15 225/45-15 225/50-15 225/60-15 225/70-15 225/75-15 235/50-15 235/60-15 235/70-15 235/75-15 245/40-15 245/50-15 245/60-15 255/60-15 255/70-15 265/50-15 265/70-15 265/75-15 275/35-15 275/50-15 275/60-15 295/35-15 295/50-15 295/55-15 295/65-15 |
16 inches
| Tire Size | Compatible Tire Sizes |
| 16 in. | 125/70-16
125/80-16 125/85-16 125/90-16 135/70-16 135/80-16 135/90-16 145/90-16 155/90-16 175/55-16 175/60-16 185-16 185/50-16 185/55-16 185/60-16 195/45-16 195/50-16 195/55-16 195/60-16 195/75-16 205-16 205/40-16 205/45-16 205/50-16 205/55-16 205/60-16 205/65-16 205/70-16 205/75-16 215/45-16 215/55-16 215/60-16 215/65-16 215/70-16 215/75-16 215/85-16 225/45-16 225/50-16 225/55-16 225/60-16 225/65-16 225/70-16 225/75-16 225/90-16 235/55-16 235/60-16 235/65-16 235/70-16 235/75-16 235/80-16 235/85-16 245/45-16 245/50-16 245/70-16 245/75-16 255/50-16 255/65-16 255/70-16 255/85-16 265/70-16 265/75-16 275/45-16 275/70-16 285/65-16 285/75-16 295/75-16 305/70-16 315/75-16 |
17 inches
| Tire Size | Compatible Tire Sizes |
| 17 in. | 115/95-17
125/70-17 125/80-17 135/80-17 135/90-17 145/70-17 145/80-17 155/70-17 155/80-17 155/90-17 165/80-17 165/90-17 195/40-17 195/45-17 205/40-17 205/45-17 205/50-17 205/55-17 215/35-17 215/40-17 215/45-17 215/50-17 215/55-17 215/60-17 215/65-17 215/70-17 225/40-17 225/45-17 225/50-17 225/55-17 225/60-17 225/65-17 225/75-17 235/40-17 235/45-17 235/50-17 235/55-17 235/60-17 235/65-17 235/70-17 235/75-17 235/80-17 235/85-17 245/35-17 245/40-17 245/45-17 245/50-17 245/55-17 245/60-17 245/65-17 245/70-17 245/75-17 255/40-17 255/45-17 255/50-17 255/55-17 255/60-17 255/65-17 255/70-17 255/75-17 255/80-17 255/85-17 265/40-17 265/60-17 265/65-17 265/70-17 275/35-17 275/40-17 275/55-17 275/60-17 275/65-17 275/70-17 285/40-17 285/65-17 285/70-17 285/75-17 295/35-17 295/70-17 305/65-17 305/70-17 315/35-17 315/70-17 335/35-17 345/40-17 |
18 inches
| Tire Size | Compatible Tire Sizes |
| 18 in. | 125/70-18
135/70-18 135/80-18 145/70-18 145/80-18 155/60-18 155/70-18 155/85-18 155/90-18 165/70-18 165/90-18 175/90-18 205/35-18 205/40-18 215/35-18 215/40-18 215/45-18 215/50-18 215/55-18 225/35-18 225/40-18 225/45-18 225/50-18 225/55-18 225/60-18 235/30-18 235/35-18 235/40-18 235/45-18 235/50-18 235/55-18 235/60-18 235/65-18 245/35-18 245/40-18 245/45-18 245/50-18 245/55-18 245/60-18 245/75-18 255/35-18 255/40-18 255/45-18 255/50-18 255/55-18 255/60-18 255/65-18 255/70-18 |
