3365 Hwy 12 E
Directions PO Box 4489
Helena, MT 59604

  • Sales: (877) 811-0582
  • Service: (877) 818-8819
  • Parts: (877) 821-2365

What You Should Know About Tire Sizes

The tire specifications are printed on the sidewall of the tire, but they are in code: P185/60R15 75H. You can decipher what the tire code means with the help of the Helena Lincoln sales team. Let's explore!

  • The first letter, or letters, indicates the type of tire, where "P" is for Passenger, "LT" means Light-Truck, "ST" stands for Special Trailer, and "T" indicates a temporary spare.
  • The "185," indicates the tire width measured in millimeters.
  • The "60" is the "aspect ratio" -- the ratio of the sidewall compared to the width. Here the height is 60% of the width.

The next letter tells you the construction of the tire:

  • R = Radial.
  • D = Diagonal, also known as a "bias-ply."
  • B = Belted, a diagonal tire with belt reinforcements.
  • The 15 is the wheel diameter in inches when measured across. It is also the size of tire that fits the wheel.
  • The 75 is the tire's load rating or load index, starting at 65, representing 639 lbs. and ending at 150, representing 7385 lbs.
  • The H designates the tire's speed rating, which is the tire's ability to dissipate heat build-up when driving long distance.

At Helena Lincoln, our service and parts technicians have the training and experience to help. They can explain the differences between tires and help pick tires suited to the way you drive. Give us a call today.

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