Tires codes

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Tires are usually named with a series of codes. For example, one of the recommended tires for Vanagons is the 'Yohohama Y356 LT 195/75 R14 (load range D)'. The latter part of this (195/75 R14) is a uniform code assigned to tires. This section tells you how to intepret this code.

Speed Rating

Sustained speed rating is designated by a letter code. Vanagons require a minimum speed rating of 'R'. (Don't be confused with 'R', though. In '195/75 R14', the 'R' is means 'radial' and is not a speed rating.)

(I'm not sure why 'H' is in there, except that some person thought it would be cool if 'H' stood for 'high speed'.)

Tire widths

Wheel diameters are usually in inches and tire width in millimeters or a letter designation. In our example of '195/75 R14', '195' is the tire width in millimeters, and '14' is the wheel diameter in inches.

Shoulder heights

The shoulder height is stated as a percentage of the tire width. For example, in '195/75 R14', the shoulder height is 75% of the tire width (195mm), or 146.25mm.

Load index

The load-index figure denotes the maximum load capacity of a tire when driven at maximum speed. Note that you have four tires, so you should multiply the load index value by approximately 4.

Vanagons & Syncros need a load rating of at least 97, while Syncro 16" need a load rating of 104.

Miscellaneous codes

Tire Diameters

  1. What is the diameter of a tire?

    Here's a table of tire diameters by width and profile, for your speedometer correction calculations. Eurotire, a nice-to-deal-with tire distributor in NJ, used to include this info and more in their catalogs.

    Diameters are in millimeters, with tire installed on narrowest rims approved for that tire size. Wider rims would give slightly smaller diameter.