|
 |
Recommended Operating Temperatures of Hoosier Sprint Tires Under Various Track Conditions
Optimum Temperature Ranges for Hoosier Sprint Tires
The following is a table with temperature limitations for Hoosier Sprint tires. Please keep in mind that there are a number of variables that must be taken into account when taking tire temperatures. Some of these variables are:
- Needle pyrometer vs. surface pyrometer vs. infrared pyrometer. The temperatures listed are from a needle pyrometer. Surface pyrometer readings will be 10 to 20% lower than needle readings. Infrared pyrometer readings should be close to surface pyrometer readings provided that the distance from the pyrometer to the tire is in the range designed for the pyrometer being used. This distance is typically about 6-8".
- The time between being at full speed on the track and taking the reading. This variable is very hard to factor out. If tire temps are high and the ambient temperatures are low the tire will cool very fast and your temperature readings will be misleading.
- Location on the tire. This includes which row of blocks on the tire and where in the block you are checking. It is best to always check the same rows. It is also best to stay at least 3/8" away from a groove or heat dissipation vent. Temperatures on the first inside row and the outer 2 rows of a 105/18 should be excluded. On left rears, the 1st inside and 1st outside rows should be excluded.
- The amount of wear the tire sees: As tread rubber wears down there is less mass to heat up so tire temps will be lower.
-
Pyrometer calibration.
These are temperature readings taken within 3 to 4 minutes after the car is at full speed on full tread depth non-grooved tires. If tire temps are below the minimum listed the tire will be slow to fire. If tire temps are above the maximum listed the tire will slow down due to fatigue or blistering. The average temperature of the tire should be within the ranges listed below. If one row on the tire is running hotter than the listed ranges try grooving that row in a circumferential direction.
D10 ambient temp up to 200°F
RD12 ambient temp up to 220°F
D12 160°F up to 250°F
RD15 160°F up to 230°F
D15 160°F up to 260°F
D20 180°F up to 260°F (unless it is a high wear situation)
F55 200°F up to 280°F
A good balance between left rear and right rear tires is also important. A good rule of thumb is that the left rear should be around 20-30°F cooler than the right rear. One exception is a high speed, high banked track like Eldora. At Eldora we typically see LR temps about equal to RR temps.
A common pitfall is that if the tires are running too hot it is not always the best thing to run a harder tire. A harder tire provides less traction (except F55) and will spin more which in turn will make it run hotter. Sometimes a softer tire will hook the car up better or grain a little. Both of these conditions will make the tire run cooler.
With "RD" type tires being high traction tires for dry slick tracks and "D" type tires being for high heat, high speed tracks, these are a few of the most common combinations:
|
 |
|
|
|
