You can use a durometer and track the hardness of the tires from when they are new and log your tests results as they age. The tires will harden with age, which can be tracked with a durometer. When using a durometer make sure that the durometer is used on tires of the same temperature to insure relative measurements. Hot tires are going to be softer than cooler tires. You will notice that tires sitting in the hot sun are softer than those that are shaded. You can use a pyrometer to improve the consistency from durometer readings.

You can also track the tire temps after a run. New tires make more heat than used tires. Worn out tires will not produce as much friction to produce tire heat. By tracking the temperature of the tires after a run, you will learn to anticipate when the temps are falling off too much. If you are diligent in your monitoring you will know when to hit the tire truck for that new set.

You can also use a tread depth gauge to check the amount of tire wear. On many tires, the grip falls off dramatically at a given wear depth. When you feel like your tires have quit, then check the depth with a tread depth gauge and write the numbers in your notebook. You will learn to anticipate when you are approaching the wear depth that makes you want a new set. Over time you can learn to predict when you have gotten the most out of your set of tires. You may find that the fall off in each corner is a bit different. The LF may work to a deeper depth than the left rear because it does not go through the spinning created by your awesome horsepower.

Another good idea is to track the number heat cycles your tires experience. Each time your tires get hot they release chemicals from deep within the rubber. As the chemicals are released the tires lose some of their grip. You can see tires that are hardly worn lose their grip due to heat cycles. Count the number of heat cycles that your tires go through and you may find a repeatable pattern that lets you know when to get that new set.