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P235/40R19 99V. Do you recognize that seemingly nonsensical string of letters and numbers? You’ve probably seen something similar on the sidewall of the tires on your vehicle, but most likely have no clue what they actually mean. It’s a lot more straightforward than you might think, with each of those letters and numbers representing something important in describing exactly what type of tire it is. In our how-to tire guide we’ll break down each number and letter, properly define it and help you understand your Toyota tire size. Follow along with us at Charlesglen Toyota and become an expert on deciphering tire sizes and ratings.

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Tire Size Letter & Number Definitions

To make things easy we’ll go across the entire string of letters and numbers one-by-one, breaking down each with their definition, and complete with an example of such letter or number you may see (found in brackets).

Tire Type (P)

This first letter refers to the tire’s type. In our case example here it’s a “P,” representing that it’s for a passenger vehicle.

Tire Width (235)

The first number that you’ll see in the string refers to the tire’s width from sidewall to sidewall, and thus the width of the rims that the tire will be mounted on. In our example here it’s 235 mm.

Aspect Ratio (40)

The second number refers to the aspect ratio of the tire, which is in reference to the height of the sidewall taken as a percentage of the width. In our case here it’s 40.

Tire Design (R)

This letter lets you know the tire design, in our case here a radial tire, which was designed to balance strength along with efficiency.

Tire Diameter (19)

This number refers to the inside diameter of the tire, the diameter of the wheel it needs to be mounted on. This time the number is in inches, and 19 in our example case here.

Tire Load Index (99)

The last number refers to the tire load index, which you might’ve guessed refers to how much weight the tire can support when it’s at its maximum air pressure. 

Speed Rating (V)

The last letter refers to the tire’s speed rating, representing a range or maximum of speed for the vehicle. The “V” in our example translates to 240 km/h (149 mph), which is for a sports car. Other examples include “S” or “T”, for 180 km/h (112 mph) and 190 km/h (118 mph), respectively, tires for family vehicles, or on the lower-end, like “L” rated at 120 km/h (75 mph), for off-road or light-duty trucks.

Additional Tire Sidewall Definitions

The above are the main tire definitions you’ll need to know to properly define your tires, but there’s a few extra ones you may see that also provide important information.

  • Manufacturing Date: This sidewall number refers to when the tire was made. It’s not the most straightforward, but is easy to understand once you know. For example, a manufacturing number of 4618 means the tire was built in the 46th week of 2018.
  • Mud & Snow or Mountain & Snowflake Symbols: These symbols represent the tire’s ability in certain conditions. They’re not entirely representative of their names, though, as the Mud & Snow symbol may come on all-season tires but doesn’t mean it’s optimal for winter use. You’ll only find the Mountain & Snowflake symbol on proper winter tires geared for the season.
  • PSI: This number refers to the max PSI that the tire is rated to. It’s important to note that you shouldn’t use this number as a guide when inflating your tire, rather you should always go by the guidance of what your owner’s manual says.

The Importance of Tire Size Numbers

Now you know what all of these jumbles of letters and numbers on the sidewall of your tires mean, but you also may be asking why they’re so important? Your Toyota was a specifically designed vehicle with a lot of thought and effort put into making it the best vehicle that it possibly can be. That means that it needs tires that match its high quality build, and ones that ensure that your Toyota’s systems can operate on the road as they should. For example, an improper width of tires can throw off your speedometer, as it was calibrated on specific tires. As well, having proper load and speed rated tires will help protect against blowouts. These are just a few reasons why it’s so important to take the time and buy tires that are made to fit and perform specifically with your vehicle.

Shop for a Tires at Charlesglen Toyota

If all of these tire numbers, letters and symbols are still a bit confusing for you, there’s no need to worry, that’s where our Charlesglen Toyota tire experts come in to save the day. Our tire centre team is more than happy to guide you through the entire process of finding and purchasing tires for your vehicle. Whether you’re ready to buy your next set, a replacement, just need a swap, or have a few questions, our service team is always here to assist.