We found that although it's something you probably won't take to bed, a tire sidewall actually makes for good reading. Pretty gripping stuff. Even if it's true that you can't tell a tire by its sidewall, the numbers and letters on its sides still can reveal some notable facts about the tire, the Goodyear folks told us. Other letter possibilities are LT for light truck and T for temporary spare. Actually, the prefix letter is optional so it might not be included in all cases.
P designates a tire primarily designed to fit passenger cars.
Other letter possibilities are LT for light truck and T for temporary spare. We should point out, however, the prefix letter is optional, so it might not be included in all cases. R means radial tire construction. Modern Tire Dealer magazine estimates 99.7 percent of the passenger tire market is radial. 17 is the wheel diameter in inches.