Many people are misinformed of what the true meaning of speed rating really is. The speed rating of your tire can be located on the sidewall of the tire just after the size. For example, your size could be P205/55R16, followed by 94V. 94 is the load index and V is the speed rating. Many people think that they don't ever drive in excessive speed so I don't need a V rated tire since I don't drive at speeds of 240km/hr! This unfortunately is not entirely true. The speed rating has to do with the overall makeup of your vehicle. When the engineers manufactured your vehicle, many tests were done in regards to performance, weight, size, handling, torque etc. The speed rating affects all of these areas. If you do not have the recomended speed rating or greater on your vehicle, when driving at higher speeds, it can affect the strength of the sidewall. It is recomended that you use the same speed rating or higher to ensure maximum performance of your vehicle. Now, if your vehicle requires a high performance speed rating, it is advised that you stick within the high performance rating. H and V are both high performance which carry very similar characteristics and is safe to interchange. S and T are your touring tires and carry similar characteristics. Please see the speed conversion table.