Tire Speed Rating (Explained) | TireGrades

One of the parts of a tire’s size is it’s speed rating. The speed rating will tell you its maximum speed capability. But this is only one aspect of how the speed rating system affects tire performance and handling characteristics.Tire manufacturers test their tires to see the fastest speed they can withstand and safely sustain speeds shown in the tire speed rating charts. But why do they do this when the maximum speed numbers are so high?It’s because these ratings are not just about speed.What Is Speed Rating On Tires?Tire speed rating is the tested top speed a tire is able to safely maintain without performance beginning to deteriorate due to the excess buildup of heat in the tire.It is represented by a single letter (with the exception of “ZR”) at the end of the tire size code.It’s unlikely your tires will ever need the maximum speed capability of their rating since they are usually well beyond the legal speed limits. But the performance improvements due to the improved heat resistan...