 e = maximum overall section width
D = external tire diameter (2 x R)
Ø = nominal bead seat diameter
H = section height
S = section width on measuring rim
(this rim is indicated in bold faced type)
E = minimum dual spacing  (on measuring rim)

There are several ways to specify a tire size, with measurements sometimes given in millimeters, sometimes in inches, or sometimes a combination of both! The tire size contains always the tire’s section width and the Rim size. The tire’s overall diameter is not always shown in the dimensions, but can be calculated from the other dimensions plus their aspect ratio. Four common examples and explanations of tire measurements & sizes given below will help you to understanding these values will help you search for your tires.

EXAMPLE: 23.5R25

• ‘23.5’ is the section width of the tire in inches.
• The ‘R’ symbolizes a Radial construction, whereas a ‘-‘ instead would mean its Crossply or Solid
• ‘25’ is the wheel/rim diameter in inches.

There is no aspect ratio (H/S) indication included in the tire size, but with this type of marking the tire sidewall height is normally taken to be 80% of the tire width. So its assumed the H/S ratio is approximately 0.80.

So, a 23.5R25 is a radial tire:

– 23.5 inches wide
– sidewall height of 18.8 inches (80% of 23.5 inches)
– overall diameter of 1625 (2 x Sidewall Height + Rim)
– fits a 25″ rim/wheel

EXAMPLE: 875/65R29

• ‘875’ is the section width of the tire in mm,
• ’65’, is the Profile of the tire (height of the sidewall expressed as a percentage of the width),
• the ‘R’ symbolizes a Radial construction
• ‘29’ is the rim size in inches

So a 875/65R29 is a radial tire:

– is 875 mm wide
– has a profile of 65% (sidewalls are 65% of 875mm = 1137 mm)
– overall diameter of 1875 mm (2 x Sidewall Height + Rim)
– fits a 29 inch rim

Example: 27.00R49

• ‘27.00’ is the section width of the tire in inches. (+ profile number percentage indication)
• The ‘R’ symbolizes a Radial construction
• ‘49’ is the wheel/rim diameter in inches.

So a 27.00R49 is a radial tire:

1. 27 inches wide
2. H/S ratio is 1 (100 series)
3. sidewall height of 27 inches (100% of 27 inches)
4. overall diameter of 2690 mm (2 x Sidewall Height + Rim)
5. fits a 49″ rim/wheel.

Example: 33×12-20

• ‘33’ is the outside diameter of the tire in inches.
• ‘12’ is the section width of the tire in inches,
• ‘20’ is the rim size in inches.
• The ‘-‘ symbolizes a Crossply of Solid construction.

So a 33×12-20 is a solid tire:

1. 33 inches tall
2. 12 inches wide
3. Solid constructed
4. fits a 20″ rim/wheel.  CONTACT