Frequently Asked Questions

QUESTIONS: 
1. What is the number written on my bias race tire in yellow chalk?
2. Explain the use of Bleeder Valves.
3. Does it matter which direction I mount my Hoosier Racing Tires?
4. How do I store my Hoosier race tires at the end of the racing season?
5. What is the (cold) inflation pressure for the new minicup tire line including mounting guidelines?
6. Why am I blistering my tires?
7. What are these lines or tiny slits on my tires?
8. What air pressure should I run in my tires?
9. Why isn’t my tire holding air?
10. Why did my tire shrink?
11. What stagger should I run?

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1. What is the number written on my bias race tire in yellow chalk?
As a result of a tire being bias in design (as opposed to radial), it will have a circumference that varies from tire to tire. After a tire is cured, it is removed from the press and placed on a machine called a "post-inflator". On this machine, each tire has air injected into it for a set period of time. After that, a tire is then measured and the circumference is recorded. Then, a press operator writes the size on the side of treaded tires and on the tread of slicks (in yellow chalk). This procedure is performed the same way for each tire to achieve consistent results.
Now, how should the chalk mark be interpreted? It should be viewed as a reference point or a guide on purchasing tires by size to attempt to attain a certain stagger. Say for instance, you needed to replace your right front tire. Your car currently has 1" of stagger (with the RF @ 28 p.s.i.) but you want to get 1 1/2" of stagger. The tire you were replacing had an original chalk mark of 86", and had a roll out, of say, 85". Obviously, you would want to purchase a tire bigger than the 86" tire you removed. Most likely, a tire with a chalk-mark of 86 1/2". You have to remember there are many factors that go into what size a tire will actually measure, the ambient temperature that day, the air pressure in the tire, whether the tire is new or old all play a role. The chalk mark does not tell you the circumference of the tire at running pressure, it does not tell you how big a tire will grow to, it tells you that a tire is either going to be bigger or smaller than another one with a different chalk mark. Once again, the chalk mark is used only as a point of reference.
2. Explain the use of Bleeder Valves.
While racing you may see that your rear tire stagger may tend to change in an unfavorable manner (while using bleeders). It may seem to be unpredictable and uncontrollable. With careful bleeder valve Set Point Management, one can effectively minimize size control problems.
Main Reason Tires May Change Size: A common problem is to see the LR tire grow while the RR tire shrinks. This tendency occurs because the RR tire runs hotter than the LR tire, causing more air pressure gain, causing the RR bleeder to relieve more pressure (volume) than the LR bleeder. Bias ply tires will change size when the air pressure changes. The higher the pressure, the bigger the tire. As a rule of thumb, the size change is linear with air pressure. A 10 psi change will either make the tire 1" bigger or 1" smaller (circumference). Each PSI is worth a .1" change in size.
Realize the use of Bleeder Valves limits the air pressure gain, but does not keep the pressure from lowering if the tire is allowed to cool. This is typically what happens during a caution period. This is when many will notice trouble with their racecar handling. Why? There is no system to replace the lost air pressure.
Bleeder Valve Recommendations: Use Bleeder Valves to reduce the air pressure buildup, not eliminate it. Bleeders should not be used to maintain a constant air pressure.
You must always set the bleeder higher than the starting cold air pressure. If your tires cool (caution period), the inflation pressure will be reduced by the amount of pressure the bleeder valve bled off. It is normal to see 7-8 psi of RR buildup (without bleeders). If the bleeders kept the RR tire at a constant pressure hot (no buildup), your car will lose .7 to .8" of stagger if the tires are given time to cool. This is not due to RR tire shrinkage; this is due to low air pressure. You may be compromising driver safety.

Recommended Initial Bleeder Valve Set Points:
Left Rear: + 3 psi over cold
Right Rear: + 4 to + 6 psi over cold
Left Front: bleeders generally not needed due to lack of tire heat
Right Front: + 5 psi minimum if used
The use of bleeders on the Right Front tire is not recommended by tire manufacturer on higher banked tracks. Reducing air pressure reduces the strength of the RF (any) tire. Bleeders may allow the RF (or any) tire to operate below the minimum safe recommended cold air pressure. You should never allow this to happen. Bleeders may be used more successfully on flat tracks to control car handling by reducing RF pressure gains.
Axle mounted Bleeder Valves need higher set points than wheel mounted bleeders: If you had a "system" that worked with wheel mounted valves, it may not work anymore. You will have to modify your thinking. This is due to the fact that axle mounted valves are more efficient at bleeding off air pressure gains. You should start off with more air pressure cold (try +2 psi) and then set you bleeders based off this higher starting pressure.    Start with these settings and make adjustments as needed. They will vary depending on the racetrack, driving style & car handling.
Adjustment example: Lets say you run an initial Bleeder Valve setup & RR comes in 1/4" smaller than it was cold, but the LR stayed the same, in which the net loss of 1/4" stagger is not desired.
You have a few options available to you, which will fix the stagger. 1) Set LR bleeder 2 psi lower, This allows the LR bleeder to release 2 psi more, which should make the LR tire about 1/4" smaller than before, making both rears - 1/4" hot. 2) Leave the LR alone & Set RR bleeder 2 psi higher. This should allow the RR tire to grow 1/4" also, keeping the stagger (and sizes) the same. 3) Leave the LR & RR bleeders alone (+3 LR,+5 RR), but lower RR cold air pressure 2 psi, this increases the gap between RR cold and bleeder set point to +7 psi. In this case, the RR tire cold will be 1/4" smaller than it was before, but it will be 1/4" bigger hot than it was before. Realize that there are several ways to fix the problem & that all we are doing is changing the gap between the cold air pressure setting and the bleeder valve set point. It is personal preference as to how you get there, realizing that you are changing the car's handling when you adjust air pressures. 
3. Does it matter which direction I mount my tires? 
Most of the asphalt tires have directional arrows on the sidewalls, if they have no directional arrows circle track tires must be mounted with the serial code located toward the infield. Every Hoosier racing tire has a four character serial code embossed into one sidewall of the tire near the bead area. Tires can be reversed or flipped but not until they have been run for at least four complete heat cycles. If this is not done the tire could be damaged and may fail. 
4. How do I store my tires at the end of the racing season? 
The useful life of a tire, whether mounted or dismounted, is directly affected by storage conditions. Tires should always be stored indoors in a dark, cool, dry room.
Remove the tires from the vehicle. 
Store tires on their side in a cool/dark/dry environment.
Place tires in a black plastic bag when stored during the "off-season".
Make sure the temperature range in the storage location is between 40-90 degrees Fahrenheit.
Don't store tires in direct sunlight or near electric motors. (Electric motors emit small amounts of ozone) Tires need to be protected from light, especially sunlight. Light causes ultraviolet damage by breaking down the rubber compounds.
Don't apply any chemical treatments to the tires. It's not necessary and may actually damage the integrity of the tire by breaking down the rubber properties of the tire. Tires must not be allowed to come in contact with oils, greases, solvents, or other petroleum products that cause rubber to soften or deteriorate.
Don't store tires in sub-freezing temperatures for any length of time. The rubber can freeze and may crack as a result.
5. What is the (cold) inflation pressure for the new minicup tire line including mounting guidelines?  
The new 15.0/7.0-8 minicup tire should be inflated to 25 psi on the right side tires and 15 psi on the left side tires. These are "cold" or starting pressures to be used as starting points. Hoosier MiniCup tires are to be mounted with the painted Hoosier logo to the outside of the car. 
6. Why am I blistering my tires? 
If it is a spec or a tire that all teams are running and it’s just one or two cars blistering the tires it is most likely a setup or driving style issue. If it is the whole field blistering tires a different tire compound may be needed. 
7. What are these lines or tiny slits on my tires?
Hoosier Racing Tire bias tire treads are strip wound which means the tread is made of a ribbon of rubber about ½” wide laid down circumferentially around the tires carcass. Sometimes these ribbons are visible as lines on the tread. In some cases there may be a slight gap between these ribbons that looks like a small slit. These slits are nothing to worry about and usually scuff out and disappear after being run. 
8. What air pressure should I run in my tires? 
Contact your local Hoosier Representative for recommended air pressures. 
9. Why isn’t my tire holding air?
Racing tires have a different construction than passenger tires and may leak or wick air from the bead area very, very slowly, losing pressure over time. Air loss may also be from a damaged wheel, cut bead or tread, or from running air pressure that is too low. 
10. Why did my tire shrink?
This may be due to misuse of a bleeder valve or adjusting air pressure too much while the tire is hot.
11. What stagger should I run?
Your local Hoosier Representative may be able to help. Check with experienced competitors. Stagger recommendations vary by track as well as chassis setup. In most cases more stagger give short-term performance advantages but shortens tire life.