It is recommended that the replacement tires match the speed symbol of the original tires since these match the speed capability of the vehicle. The 300 is treadwear, which represents the tire's comparative wear when measured against the government mandated tire which is rated at 100. So this tire wore three times longer than the control tire. Traction indicates the level of grip the tire possesses. Temperature rating deals with the tire's ability to disperse built-up heat.
Heat causes rubber to deteriorate over time, so dispersing heat increases tire.
Each tire manufacturer determines UTQG rating for their products. Realize that UTQG's are more accurate when comparing tires within the same line versus tires from two different makers. All rights reserved.