Tire Size Chart

The Tire Size Chart is a sizing reference tool covering tire size chart, tire size conversion chart, tire size meaning, tire size comparison chart. Use the chart below to look up values instantly. Printable and downloadable versions are available on this page.

Tire Size Calculator

Enter your current tire size and an alternate size to compare diameters, check speedometer error, and verify rim fitment.

Current Tire Size
Alternate Tire Size
Current Diameter (in)
Alt Diameter (in)
Diameter Diff (in)
Speedo Error %
Current Rev/Mile
Alt Rev/Mile
Hero image for a tire size chart tool with centered "Tire Size Chart" text, a tire size calculator UI panel with input field, dropdown, toggle, and Generate button, set over a realistic automotive garage scene for accurate tire size conversion.

How to Read a Tire Size

1
Find the tire size code on your tire's sidewall — it looks like P225/65R17 91H. Each part of this code tells you something specific about the tire.
2
The first letter(s) indicate the tire type. P means Passenger. LT means Light Truck. ST means Special Trailer. No letter indicates a metric tire.
3
The three-digit number is the section width in millimetres — how wide the tire measures across its widest point. Example: 225 means 225 mm wide.
4
The two-digit number after the slash is the aspect ratio — the sidewall height expressed as a percentage of the section width. Example: 65 means the sidewall height is 65 percent of 225 mm which equals 146 mm.
5
The letter after the aspect ratio indicates the construction type — R means Radial (standard on all modern passenger tires). The number after R is the rim diameter in inches. Example: R17 means the tire fits a 17-inch rim.

Tire Size Reference Chart — Common Sizes

Common Tire Sizes — Section Width, Sidewall Height, Diameter, and Revolutions Per Mile
Tire Size Code Section Width (mm) Sidewall Height (mm) Rim Diameter (in) Overall Diameter (in) Revolutions Per Mile
195/65R151951271524.2851
205/55R162051131624.9826
215/55R172151181726.3784
215/60R162151291625.6804
225/45R172251011725.0823
225/50R172251131725.9797
225/60R162251351626.6775
225/60R172251351727.6747
225/65R172251461728.5723
235/55R172351291727.2757
235/60R172351411728.2731
235/65R172351531729.0711
245/45R182451101826.7772
255/50R192551281929.1709
255/60R182551531830.1685
265/65R172651721730.6674
265/70R172651861731.6652
275/55R202751512031.9645
285/75R162852141632.8628
305/50R203051532032.1643

Source: Tire and Rim Association standard size calculation

Tire Speed Rating Chart

Tire Speed Rating Chart — Complete Reference
Speed Rating Symbol Maximum Speed (mph) Maximum Speed (km/h)
L75 mph120 km/h
M81 mph130 km/h
Q99 mph160 km/h
R106 mph170 km/h
S112 mph180 km/h
T118 mph190 km/h
H130 mph210 km/h
V149 mph240 km/h
W168 mph270 km/h
Y186 mph300 km/h
Z149+ mph240+ km/h — see manufacturer for exact limit
ZR150+ mph240+ km/h — used on ultra-high-performance tires
Never fit a tire with a lower speed rating than your vehicle's original specification. Going higher is acceptable and provides additional safety margin.

Source: Tire and Rim Association (TRA) speed rating standards

Tire Load Index Chart

Tire Load Index — Maximum Load per Tire
Load Index Maximum Load (lbs) Maximum Load (kg)
75853 lbs387 kg
80992 lbs450 kg
851,135 lbs515 kg
901,323 lbs600 kg
951,521 lbs690 kg
1001,764 lbs800 kg
1052,039 lbs925 kg
1102,337 lbs1,060 kg
1152,679 lbs1,215 kg
1203,086 lbs1,400 kg

Source: Tire and Rim Association load index standards

Tire Size Calculator

Enter your current tire size and compare to an alternate size to get the diameter difference, speedometer error percentage, and RPM change. The rim fitment checker confirms whether the alternate tire fits your existing wheels.

Current Tire Size
Alternate Tire Size
Current Diameter (in)
Alt Diameter (in)
Diameter Diff (in)
Speedo Error %
Current Rev/Mile
Alt Rev/Mile

Frequently Asked Questions

What does P225/65R17 mean?

P means Passenger tire. 225 is the section width in mm, 65 is the aspect ratio (sidewall height as a percentage of width), R means Radial construction, and 17 is the rim diameter in inches.

How do I find the correct tire size for my car?

Your vehicle's recommended tire size is on a sticker inside the driver's door jamb — it shows the OEM size, recommended inflation pressure, and load index. It is also listed in your owner's manual.

Can I put a different size tire on my car?

You can fit different sized tires but the overall diameter should remain within 3 percent of the original to avoid affecting speedometer accuracy, fuel economy, and vehicle dynamics. Use a tire size calculator to compare overall diameters before purchasing.

What is plus sizing in tires?

Plus sizing means fitting a larger rim diameter with a lower-profile tire so the overall diameter stays approximately the same. This improves handling precision and appearance while maintaining correct speedometer calibration.

What does the load index number mean?

The load index is a code that represents the maximum weight one tire can safely carry. A load index of 95 means the tire supports up to 1,521 lbs per tire — for four tires this equals a maximum vehicle load of 6,084 lbs.

How do I know when my tires need replacing?

The legal minimum tread depth in most US states is 2/32 inch — test this with a penny inserted into the tread groove and check if Lincoln's head is fully visible. Most safety experts recommend replacing at 4/32 inch which gives significantly better wet weather stopping distance.

What is the difference between P and LT tires?

P (Passenger) tires are designed for cars, crossovers, and light SUVs with normal loads. LT (Light Truck) tires are built with heavier construction for trucks, full-size SUVs, towing, and carrying heavy loads — they run at higher inflation pressures.

What does the speed rating H mean on a tire?

The H speed rating means the tire is certified for speeds up to 130 mph (210 km/h). H-rated tires are standard on many performance sedans and sports cars and offer a good balance of performance and longevity.

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