A depth gauge, like this one...
A depth gauge, like this one from Longacre, is always valuable. Make sure to scrape off excess rubber, as the racer on the previous page is doing, if you check depth after the car has been on the track.
Successful race teams, whether in Late Model or Street Stock classes, should have a team member designated to concentrate on tires. Every team needs that because the tires, and the variables that affect them, change every time the car rolls onto the track.
However, if you don't have the luxury of having that person, stay on top of everything, the importance of taking and keeping notes on your tires can't be over-emphasized. Also, keep records of the temperature of the track and the ambient temperature. With time, you will be able to understand how different things affect the tires and will be able to prepare for those changes to improve your finish at the track.
It is extremely important to know exactly where the optimum pressures are for the tires you are running. Each tire manufacturer has determined the air pressure where tires have the maximum amount of grip. So check with your manufacturer and determine the optimum pressure for your tires.
Don't release the built-up...
Don't release the built-up air pressure before the tire has had a chance to cool down, as it will lose air once it starts to cool.
Intercomp makes a spring rate tester for tires. This device can be used to allow the buyer of tires to hone in on exactly which tire will be beneficial for the intended application. This is perfect for Late Model drivers who show up at the track and get a set of tires to use for the day. With the tester, the spring rate of the tire can be determined and the racer will know exactly which tire's sidewall is stiffer than the others. So, if a tire is 175 pounds less than the other tires, it will be obvious that this one has had a very extensive life.
Of course, these are exaggerated scenarios, but more than anything, the spring rates of the tires are a point of reference when you are trying to determine what changed week to week.
Alan Gaston, a BF Goodrich engineer, puts it best: "If you run a coil-bind setup, the tire's spring rate will come into play largely. With the spring completely compressed, the tire's sidewall will now act as the spring for the car."
The tire's sidewall will again be put through extreme circumstances that demand the tire not be under-inflated.
Every time the car comes off...
Every time the car comes off the track, the first thing you should do is gather the air pressures and tire temperatures before you start doing anything else.
Before investing in a spring rate tester, though, be aware that spring rates should be checked in a controlled environment. The spring rates of the tires depend on everything that affects the tire. The tester needs to be in an air-conditioned room and the tires should be checked with air pressures set at levels where the hot pressure is going to be, not where they'll be at the start of the race. The more pressure in the tires, the more the spring rate will be. Also make sure to use nitrogen; otherwise the moisture in the tires will throw off the spring rate.
Street Stock and Late Model drivers who race on asphalt can go through a set of tires quickly. Fortunately, most Street Stock classes are equipped with a spec tire rule to even out the competition and to offset the costs of weekly racing. The tires, depending on how many times you decide to wreck them, will last almost a full season. Soaking or prepping of the tires is not allowed in the Street Stock classes. Hickory (North Carolina) Motor Speedway will actually fine teams $1,000 if caught soaking tires in the Street Stock division.
Asphalt Late Model drivers could only be so lucky to have a set of tires last a full season. Many tracks are going to a rotation system for tires. Prior to the first event a team runs at a particular track, the team will purchase four tires, race on them, and at the end of the night designate two tires to be used the following week. Those two tires are left at the track. The following week the team will have to purchase only two more tires, not four, thus saving money.