Tire Speed Ratings with Chart
Speed ratings identify the maximum speed a tire can sustain for 10 minutes without being in danger. Higher speed rated tires are less likely to have catastrophic sidewall damage or tread failure. Even though your speed rating indicates the maximum speed your tires are equipped to handle, it does not mean your vehicle can safely operate at that speed.
When purchasing new tires, be aware that speed ratings are determined during simulated road performance tests on unstressed and properly inflated tires. New tires should also have the same or a higher speed rating than a vehicle’s original equipment tires to maintain or improve its performance.
A tire’s speed rating is located within the tire size on the sidewall. If the size features two letters, the first letter signifies the speed rating, and the second letter indicates it’s a radial.
Porsche N-Rated Tires
To obtain the highest performance from their vehicles, Porsche introduced N-rated tires. N rated tires deliver optimum dry surface handling and impressive wet surface traction.
Porsche integrates their automobile development with their tire specifications. Porsche engineers work in joint ventures with tire manufacturers during development and testing to produce Porsche OE tires and approved replacements. The tires must pass a series of tests to prove they can sufficiently support a Porsche at its top speed on the German Autobahn. These tests include a series of lab tests, and track and race tests to evaluate a tire’s high-speed durability, uniformity and serviceability.
Tires are assigned an N rating only after meeting Porsche standards. The N ratings are labeled N-0, N-1, N-2, N-3 and N-4 and are marked on the sidewall of the tire. For a completely new design, the tire will be labeled N-0. As improved versions of the tire are developed, it will be labeled N-1 and so on.
N-rated tires are engineered for a specific vehicle or range. When replacing N-rated tires, they should at the least be changed in pairs on the same axle. Replacement tires need to be the same make and rating as your Porsche’s current tires. In instances of damage, an individual tire should only be replaced if the remaining tire on the axle’s wear hasn’t exceeded 30%. If the tire has more than 30% wear, the pair should be replaced.