How Do I Read a Tire Size

Download Commodity

Download Article

You may demand to know the size of your tires for various reasons, such as for a spare tire or when purchasing wheels, rims, or snow tires. Still, measuring the tire size manually with a tape measure out will not give you accurate results. Luckily, your tire size is like shooting fish in a barrel to figure out. Simply read the series of letters and numbers printed on the tire sidewall—all the information you need is right there!

ane
Find the series of numbers on the sidewall. Tires are manufactured with the tire size printed on the sidewall. The sidewall is the outer wall of the tire, rather than the tread that contacts the road. The size should be printed underneath the tire manufacturer name, just above the rim of the tire.^[1] ^[2]
- For instance, the series may look like this: P 225 / 50 R 17 98 H
2

Recognize that the beginning letter denotes the service type. On some tires, the serial of numbers begins with a letter of the alphabet. "P" stands for "P-metric" and denotes a passenger vehicle.^[3] "LT" stands for lite truck, "T" means temporary spare, and "C" stands for commercial. If you're purchasing a spare or new tire, you'll need to choose the same service blazon as the rest of the tires.^[4]

Advertisement
3
Note that the first 3-digit number identifies the tire width. The three-digit number earlier the slash denotes the tire width, which is measured from sidewall to sidewall and corresponds to the tread that contacts the road. The measurement is given in millimeters, and all 4 tires must have the same width.^[5]
- For example, if the starting time number is 225, the tire tread is 225 mm wide.
iv
Understand that the following 2-digit number is the aspect ratio. The numbers after the slash indicate the aspect ratio, which compares the tire's section height with the tire'southward section width.^[6] If you lot're replacing only one tire, make certain it has the aforementioned aspect ratio as the others.^[vii]
- For example, if there is a "50" after the slash it means the tire's section height is l% of the tire's section width.
Advertisement

one

Understand that the adjacent letter of the alphabet corresponds to the tire casing. Subsequently the aspect ratio, a unmarried letter will exist listed that denotes how the tire was constructed. "R" means radial construction, "B" stands for belted bias, and "D" means diagonal bias construction. Cull a spare or new tire with the same casing and construction as the rest.^[8]
2
Recognize that the next two-digit number tells the rim diameter. Later on the letter, there volition be a 2-digit number. This number gives the measurement, in inches, of the rim diameter, which is essential to know if you lot're getting new rims or wheels.^[nine]
- For instance, if the number is 17, your rims are 17 inches (43.2 cm) in diameter.
3
Annotation that the terminal combination is the load alphabetize and speed rating. The final combination of letters and numbers is chosen the service clarification. The load index refers to the load-conveying capabilities of a properly-inflated tire, while the speed rating tells you the maximum speed the tire can handle.^[x]
- The load index number corresponds with a load index chart, and does non tell you the weight in pounds. For case, a load alphabetize of 98 tin carry 1,653 pounds.^[11]
- Speed ratings are lettered A–Z and represent to a speed rating nautical chart. For example, the letter of the alphabet H indicates a maximum speed of 130 mph.
Advertisement

Add together New Question

Question

What is the difference between 185/14 and 195/fourteen?

The larger number but represents the distance from bead to bead, so 195/xiv would be slightly larger.
Question

What'southward the tire size for 1998 Contrivance Neon?

Check the driver'southward side door. In that location should be a label there indicating the correct tire force per unit area and tire sizes. You tin too check on the sidewall of the actual tires you have on the car at present, it should exist conspicuously printed on the side.
Question

If my vehicle was factory-equipped with 255/55 R18 tires, tin I change to 265/55 R18 if I change all four tires?

Logic Johnson Lafontaine

Top Answerer

Tin you just swap them? No. You'll need new wheels to put them on considering the new tires will take slightly bigger sidewalls. You besides need to be sure the manufactory tires aren't max size, considering the new ones are 10 mm wider.
Question

What size tire replaces a B78-xiii?

Nicholas Ivey

Customs Answer

About times, information technology'due south 175/80/13 for a vehicle (motorcar) either Lt or P, or any vehicle.
Question

Temporary tires are slim and lower in pinnacle, using information technology with other three higher tires, will information technology not affect chassis or vehicle trunk?

Nicholas Ivey

Community Answer

Depending on the tire size for a passenger vehicle or low-cal truck vehicle and the weight (pounds) of your car, wide tires on a light vehicle=lower psi. Skinny tires on a heavy vehicle=higher psi.
Question

What size tire can I supersede my 215/65r 17s with?

Nicholas Ivey

Community Reply

That is non a tire size for a vehicle (car), so it'southward impossible to replace the tires.
Question

I need to replace four Continental P 215/l R17 91H tires for a 2022 Ford Focus five-door. I'd similar to go to a wider tire, perhaps 225 or wider. Rims are 7". Can I do that due west/o going to 18" wheels?

Nicholas Ivey

Community Answer

If there is enough clearance for the wider tires on your car, yes, it volition fit on your vehicle.
Question

What does the tt in 12.00R20-20PR TT mean?

Nicholas Ivey

Community Answer

TT = transit time of your tires for your vehicle (auto).
Question

I accept a 5 lug 215/70R15 1968 Dodge sportsman and want to trade out the tires. What can I utilize to fit?

Nicholas Ivey

Community Reply

You can't trade out the tires. You have to buy the same stock of manufactured tires.
Question

Trying to purchase spare tire cover for Goodyear 235/65/17. What size exercise I need?

Nicholas Ivey

Community Answer

There are two options. 235/65 R17 and 245/65 R17. Original equipment tire was probably a Goodyear.