May 04, 2022 - 11:40 PM
Thank you for reaching out. The number 121 represents the load index, this means that the tire can withstand a load up to 3,297 lbs per tire. The letters R, Q and S represent the speed rating. Speed Rating (Q) indicates the tire is approved for speeds up to 99mph under optimal conditions. Speed Rating (R) is approved for speeds up to 106mph and Speed Rating (S) up to 112mph under optimal conditions. If you would like to learn more about Speed and Load Ratings you can read our blog here. Let us know if you have any further questions.