Have you ever gone tire shopping and been baffled by looking at the size chart? It may be pretty tricky looking at those profound numbers and complicated symbols and having no clue what they signify. In the worst-case scenario, you may wind up purchasing ones that do not correctly fit your vehicles’ requirements. Another issue is that using the wrong ones is wasteful and even unsafe.
Knowing how to identify the suitable size for your car may save you time, hassle, and money. And as a car owner, this implies a lot. Yet, few people aren’t familiar with those mixed numbers and letters displayed on the sidewall.
Fortunately, this post is all about knowing how to read tire sizing, the meanings, measurements & chart guide. Keep on reading!
Importance of Finding the Proper One
Yes, tires must materially match into your car, but a few additional reasons why having the proper size is so important.
As per common perception, the only fundamental car component that touches the road is the tires. They are a part of a wheel set up built to support a vehicle’s entire weight. Aside from that, they are designed to absorb shocks and vibrations, convey traction controls, speed, and braking forces to the road surface, and keep and alter the direction of motion. They may come with resilient rubbers and are loaded with compressed air to accomplish such functions. Still, the incorrect tire one may hamper your car’s performance and possibly endanger you on the road.
When it comes to tire changes, once you’ve settled on the type for your vehicle, you should stick with the same size upon replacement. This is because having a different sized ones may distort your gauges, as well as impair your vehicle’s safety systems and stability control.
Switching bigger tires with the wrong sidewall diameter can compromise your vehicle’s steering system, wheels, and tires, as well as give false speedometer readings. The same may be said when switching smaller tires.
If at all can, adhere to the same brand and size because combining various complimentary items to form a matched set may deter your vehicle’s overall performance.
Dimensions Explained
There are two types of measurements; metric and flotation.
Metric units is used for most tires purchased by the general public and is relatively difficult to understand. P265/50R20 is one example.
There are six (6) sections in metric sizing.
#1. First letter in
The tire type is the first letter in the code that indicates what class it is
- P designates for passenger vehicle tires, including cars, minivans, SUVs, small pickup trucks, and sedans.
- LT class stands for light truck, for vehicles carrying medium loads, trailers, and other vehicles used for rough driving conditions, as well as pickups and vans hauling heavy loads.
- ST means special trailer tires designed for vehicles carrying heavy loads, utility trailers, and boat trailers.
- T is for temporary rated or spare tires for speeds not exceeding 50 mph and for emergencies or driving just enough to get to a garage shop.
If it does not have the initial letter specified, it is most likely a passenger tire. Make careful you double-check the load rating.265
#2. Width
The 3-digit number after the first letter is the width section. It (265) defines the width from sidewall to sidewall in millimeters when seen from the front.
#3. Aspect Ratio
The aspect ratio, often known as the tire profile size, reflects the sidewall’s size in proportion to the section width. In this example, “50” indicates that the sidewall is 1⁄2 of the width. Or 5.2″—the higher or taller the sidewall, the higher or taller the ratio.
The following code is to determine the type of construction. In this example, R indicates that it is a radial structure.
- Radial ® tires now account for 98 percent of all the ones manufactured. Most vehicle owners prefer them because of their improved grip, gas mileage, and durability. The plies of radial these types are placed perpendicular to the direction of movement. It also indicates a mix of polyester cloth and steel covered with rubber.
- D-reading is present in some tires. It is an abbreviation for a diagonal ply or bias-ply, often known as the traditional X or cross-ply. This indicates that the plies are crisscrossed.
- Another letter is B, which denotes belt constructions, which are commonly seen on bikes or trailers. They’re much the same as in D, except they feature a belt that passes beneath the thread region.
- F is another type that simply indicates “run flat.” Simply said, it runs flat after being ruptured for a short period.
#4. Wheel Diameter
In inches, the wheel diameter is a two-digit value that represents the diameter of the wheel. It uses the same coding for the metric and US standard systems.
#5. Load Index or Service Description Rating
Load index or service description rating is used to identify your load factor and speed rating. It denotes how much weight a tire can hold based on a conventional tire chart.
#6. Speed Rating
The speed rating refers to the speed rating. It shows the maximum speed at which it is safe to drive over an extended time. A more excellent speed rating can withstand more heat. As the speed rating increases, so does the construction quality and tire durability. A high rating, in some ways, also indicates a higher price.
Flotation sizing is simpler than metric sizing. A 40×25.50 R22LT flotation example is 40 inches tall, 5.5 inches wide, and fits your 22-inch tire.
Where to Find the Number to Look For?
An extensive tire size chart with metric and inch sizes easily compared all models. Each metric measurement includes both the metric size and the inch equivalent. To convert the metric unit to an inch, multiply the first number by the second number divided by 100, which gives you the sidewall height in millimeters, then divide that by 25.4 to convert it to an inch. The overall diameter is then calculated by multiplying the wheel diameter by two sidewall measures and then dividing the first value by 25.4 to get the width in inches.
Tire Chart by Wheel Size and Diameter
Here is a chart that lists every tire by wheel size and diameter to make your search as easy as possible.
chart for 13” wheels
Check below to see the various options for 13″ wheels. The upper number signifies the diameter.
| 21″
185/60R13 = 21.7×7.3R13 215/50R13 = 21.5X8.5R13 225/45R13 = 21×8.9R13 225/50R13 = 21.9×8.9R13 255/40R13 = 21x10R13 |
22″
155/80R13 = 22.8×6.1R13 175/70R13 = 22.6×6.9R13 205/60R13 = 22.7×8.1R13 22X8R13 |
23″
165/80R13 = 23.4X6.5R13 185/70R13 = 23.2×7.3R13 |
| 24″ Diameter
175/80R13 = 24×6.9R13 185/80R13 = 24.7×7.3R13 24.5X8R13 24.5X9R13 |
Chart for 14” wheels
| 19″
105/70R14 = 19.8X4.1R14 |
20″
115/70R14 = 20.3X4.5R14 125/70R14 = 20.9X4.9R14 |
21″
165/55R14 = 21.1X6.5R14 |
| 22″
135/80R14 = 22.5X5.3R14 165/65R14 = 22.4×6.5R14 185/55R14 = 22×7.3R14 185/60R14 = 22.7×7.3R14 195/55R14 = 22.4×7.7R14 205/50R14 = 22.1×8.1R14 205/55R14 = 22.9×8.1R14 225/50R14 = 22.9×8.9R14 |
23″
175/65R14 = 23×6.9R14 175/70R14 = 23.6×6.9R14 185/65R14 = 23.5×7.3R14 195/60R14 = 23.2×7.7R14 205/60R14 = 23.7×8.1R14 |
24″
185/70R14 = 24.2×7.3R14 185/75R14 = 24.9X7.3R14 195/65R14 = 24×7.7R14 195/70R14 = 24.7×7.7R14 215/60R14 = 24.2×8.5R14 225/60R14 = 24.6×8.9R14 |
| 25″
185R14 = 25.7×7.3R14 195/75R14 = 25.5×7.7R14 205/70R14 = 25.3×8.1R14 215/70R14 = 25.9×8.5R14 235/60R14 = 25.1×9.3R14 245/60R14 = 25.6×9.6R14 |
26″
195R14 = 26.2×7.8R14 205/75R14 = 26.1×8.1R14 215/75R14 = 26.7×8.5R14 225/70R14 = 26.4×8.9R14 26X8.5R14 |
27″
205R14 = 27×8.2R14 27X8.5R14 27X9.5R14 |
| 28″
28X10R14 |
30″
30X10R14 |
Chart for 15” wheels
| 20″
105/70R15 = 20.8X4.1R15 |
21″
115/70R15 = 21.3X4.5R15 125/70R15 = 21.9X4.9R15 165/50R15 = 21.5X6.5R15 195/45R15 = 21.9×7.7R15 |
22″
125/80R15 = 22.9X4.9R15 145/65R15 = 22.4×5.7R15 155/60R15 = 22.3×6.1R15 165/60R15 = 22.8×6.5R15 175/55R15 = 22.6×6.9R15 195/50R15 = 22.7×7.7R15 22X8R15 22.5X4.5R15 245/40R15 = 22.7X9.6R15 275/35R15 = 22.6×10.8R15 |
| 23″
135/80R15 = 23.5X5.3R15 165/65R15 = 23.4X6.5R15 175/60R15 = 23.3×6.9R15 185/55R15 = 23×7.3R15 185/60R15 = 23.7×7.3R15 195/55R15 = 23.4×7.7R15 205/50R15 = 23.1×8.1R15 205/55R15 = 23.9×8.1R15 225/45R15 = 23×8.9R15 225/50R15 = 23.9×8.9R15 295/35R15 = 23.1X11.6R15 |
24″
135/90R15 = 24.6X5.3R15 155/80R15 = 24.8X6.1R15 175/65R15 = 24×6.9R15 185/65R15 = 24.5×7.3R15 195/60R15 = 24.2×7.7R15 205/60R15 = 24.7×8.1R15 225/55R15 = 24.7×8.9R15 235/50R15 = 24.3×9.3R15 24X4.5R15 24X5R15 24.5X8R15 245/50R15 = 24.6×9.6R15 345/35R15 = 24.5×13.6R15 |
25″
165/80R15 = 25.4X6.5R15 185/70R15 = 25.2×7.3R15 195/65R15 = 25×7.7R15 195/70R15 = 25.7×7.7R15 205/65R15 = 25.5×8.1R15 215/60R15 = 25.2×8.5R15 225/60R15 = 25.6×8.9R15 265/50R15 = 25.4X10.4R15 275/50R15 = 25.8×10.8R15 |
| 26″
205/70R15 = 26.3×8.1R15 215/65R15 = 26×8.5R15 215/70R15 = 26.9×8.5R15 235/60R15 = 26.1×9.3R15 245/60R15 = 26.6×9.6R15 26X10R15 26X10.5R15 26X11.5R15 26X6R15 26X7.5R15 26X8R15 26X8.5R15 295/50R15 = 26.6×11.6R15 |
27″
205/75R15 = 27.1×8.1R15 215/75R15 = 27.7×8.5R15 225/70R15 = 27.4×8.9R15 255/60R15 = 27x10R15 27X10.5R15 27X9.5R15 27.5X4.5R15 295/55R15 = 27.8X11.6R15 325/50R15 = 27.8×12.8R15 E78-15 = 27×6.5R15 |
28″
225/75R15 = 28.3×8.9R15 235/70R15 = 28×9.3R15 235/75R15 = 28.9×9.3R15 245/70R15 = 28.5X9.6R15 255/65R15 = 28.1x10R15 275/60R15 = 28×10.8R15 28X10.5R15 28X11.5R15 28X12.5R15 28X13.5R15 28X4.5R15 28X7.5R15 28X9R15 |
| 29″
215/85R15 = 29.4X8.5R15 255/70R15 = 29.1x10R15 265/70R15 = 29.6×10.4R15 29X10.5R15 29X11.5R15 29X12.5R15 29X15.5R15 29X18R15 29X18.5R15 29X4.5R15 29X8.5R15 29.5X11.5R15 29.5X13.5R15 29.5X9R15 315/60R15 = 29.9×12.4R15 7R15 = 29.5×7.7R15 |
30″
255/75R15 = 30.1x10R15 265/75R15 = 30.6×10.4R15 295/65R15 = 30.1×11.6R15 30X10R15 30X10.5R15 30X11.5R15 30X12.5R15 30X13.5R15 30X7R15 30X9R15 30X9.5R15 |
31″
31X10.5R15 31X11R15 31X11.5R15 31X12.5R15 31X13R15 31X13.5R15 31X14.5R15 31X16.5R15 31X18R15 31X18.5R15 31X9.5R15 |
| 32″
32X10.5R15 32X11.5R15 32X14R15 32X16R15 32X17.5R15 32X18.5R15 32X9.5R15 |
33″
33X10.5R15 33X11.5R15 33X12.5R15 33X13R15 33X13.5R15 33X14R15 33X14.5R15 33X15.5R15 33X16.5R15 33X19.5R15 33X21.5R15 33X9R15 33X9.5R15 |
34″
34X10.5R15 34X12.5R15 34X9.5R15 |
| 35″
35X10.5R15 35X12.5R15 35X13.5R15 35X14.5R15 35X15R15 35X15.5R15 35X16R15 |
36″
36X12.5R15 36X13.5R15 36X14.5R15 |
37″
37X12.5R15 37X13R15 37X13.5R15 37X14R15 37X14.5R15 |
| 38″
38X12.5R15 38X13R15 38X14.5R15 38X15.5R15 38.5X11R15 38.5X13.5R15 38.5X14.5R15 38.5X15R15 38.5X16R15 |
39″
39X13.5R15 39.5X13.5R15 39.5X15R15 39.5X18R15 |
40″
40X16R15 |
| 42″
42X14R15 42X15R15 42.5X13.5R15 |
44″
44X18.5R15 44X19.5R15 44X21R15 |
47″
47X17R15 |
Chart for 16.5” wheels
| 29″ Diameter
8.75R16.5 = 29.5×8.8R16.5 |
30″ Diameter
9.5R16.5 = 30.6×9.5R16.5 |
32″ Diameter
32X12R16.5 |
| 33″ Diameter
33X11.5R16.5 33X12.5R16.5 33X14R16.5 33X14.5R16.5 33X15.5R16.5 |
35″ Diameter
35X12.5R16.5 35X14.5R16.5 35X15R16.5 35X15.5R16.5 35X16R16.5 35X9.5R16.5 |
36″ Diameter
36X12.5R16.5 36X13.5R16.5 36X14.5R16.5 36X16R16.5 |
| 37″ Diameter
37X12.5R16.5 37X13R16.5 37X14R16.5 |
38″ Diameter
38X11R16.5 38X12.5R16.5 38X15.5R16.5 38.5X11R16.5 38.5X13.5R16.5 38.5X14.5R16.5 38.5X15R16.5 38.5X16R16.5 |
42″ Diameter
42X14R16.5 42X15R16.5 42.5X13.5R16.5 |
| 44″ Diameter
44X18.5R16.5 44X18.5R16.5 44X19.5R16.5 44X21R16.5 |
Chart for 25” diameter
| 14″ Wheel
185R14 = 25.7×7.3R14 195/75R14 = 25.5×7.7R14 205/70R14 = 25.3×8.1R14 215/70R14 = 25.9×8.5R14 235/60R14 = 25.1×9.3R14 245/60R14 = 25.6×9.6R14 |
15″ Wheel
165/80R15 = 25.4X6.5R15 185/70R15 = 25.2×7.3R15 195/65R15 = 25×7.7R15 195/70R15 = 25.7×7.7R15 205/65R15 = 25.5×8.1R15 215/60R15 = 25.2×8.5R15 225/60R15 = 25.6×8.9R15 265/50R15 = 25.4X10.4R15 275/50R15 = 25.8×10.8R15 |
16″ Wheel135/90R16 = 25.6X5.3R16 145/80R16 = 25.1X5.7R16 195/60R16 = 25.2×7.7R16 205/60R16 = 25.7×8.1R16 215/55R16 = 25.3×8.5R16 225/55R16 = 25.7×8.9R16 245/50R16 = 25.6×9.6R16 265/45R16 = 25.4X10.4R16 275/45R16 = 25.7×10.8R16 315/40R16 = 25.9X12.4R16 |
| 17″ Wheel
115/95R17 = 25.6X4.5R17 135/80R17 = 25.5X5.3R17 145/70R17 = 25X5.7R17 155/70R17 = 25.5X6.1R17 205/50R17 = 25.1×8.1R17 205/55R17 = 25.9×8.1R17 215/50R17 = 25.5X8.5R17 225/45R17 = 25×8.9R17 225/50R17 = 25.9×8.9R17 235/45R17 = 25.3×9.3R17 245/45R17 = 25.7×9.6R17 255/40R17 = 25x10R17 265/40R17 = 25.3×10.4R17 275/40R17 = 25.7×10.8R17 295/35R17 = 25.1×11.6R17 315/35R17 = 25.7×12.4R17 |
18″ Wheel
135/70R18 = 25.4X5.3R18 155/60R18 = 25.3X6.1R18 215/45R18 = 25.6×8.5R18 225/40R18 = 25.1×8.9R18 235/40R18 = 25.4×9.3R18 245/40R18 = 25.7×9.6R18 255/35R18 = 25x10R18 265/35R18 = 25.3×10.4R18 275/35R18 = 25.6×10.8R18 285/35R18 = 25.9×11.2R18 295/30R18 = 25×11.6R18 305/30R18 = 25.2x12R18 315/30R18 = 25.4×12.4R18 335/30R18 = 25.9×13.2R18 |
19″ Wheel115/70R19 = 25.3X4.5R19 125/70R19 = 25.9X4.9R19 225/35R19 = 25.2×8.9R19 235/35R19 = 25.5×9.3R19 245/35R19 = 25.8×9.6R19 255/30R19 = 25x10R19 265/30R19 = 25.3×10.4R19 275/30R19 = 25.5×10.8R19 285/30R19 = 25.7×11.2R19 315/25R19 = 25.2×12.4R19 |
| 20″ Wheel
215/30R20 = 25.1X8.5R20 225/30R20 = 25.3×8.9R20 235/30R20 = 25.6×9.3R20 245/30R20 = 25.8×9.6R20 275/25R20 = 25.4X10.8R20 285/25R20 = 25.6×11.2R20 295/25R20 = 25.8×11.6R20 |
Types
Touring
Touring ones provide a smoother ride, adequate wet and dry grip, increased winter traction, however not suitable in summer drive, a comfortable drive, and extended tread life.
Performance
These emphasize quick-handling, improved wet and dry grip, adequate winter traction, a sporty quality, and more pointed tread life.
All-terrain
Engineered for daring, with exceptional off-road traction, but louder and firmer on surface streets. Winter traction is adequate, and the wear life is sufficient.
Winter
Winter ones are specialists in snow, sleet, and ice grip and are designed to drive in low temperatures.
Track
These are for the racetrack, autocross, or drag strip, and the tires have incredible track performance, agile handling, and short wear life. Some are appropriate for usage on the street.
Special service
Trailer service tires that are designed for balance, endurance, and loading.
