Hoosier TDs curious as to what tire pressures others run.

[Tom1200]

I run a 185/60-13 Hoosier Street TD on my 1200 race coupe. I have been running 24 psi hot. I noticed a guide form one of the distributors said 1500-2000lb car run 18-20 hot. I tried 22psi this past weekend and not sure it is an improvement so 20 seems rather low. For those who don't know these are bias ply which run lower than radials.

 

Tom

[datzenmike]

Follow the suggested air pressures on the side wall. Never run lower if possible. Lower pressures allow the tire to bulge and flex as it turns. This flexing generates internal heat. Heat will shorten the life and can cause sudden failure. Now having said that, if in town the heat generated is much less than at 70 MPH on the highway. Also different tires dissipate heat faster than others. If the ride is too firm run the lowest recommended tire pressures. If carrying a heavy load, and/or 4 passengers for any distance always air up the tire to reduce flexing and heat build up and lower at end of trip.

 

Remember the trouble Firestone had 15  years ago? Sudden tire failures on Ford Exploders (and others)? Generally the vehicles tended to roll over on hard turns. Rather that fix the problem they recommended the tire pressure be reduced below the recommended lower limit to only 26 PSI. Internal heat slowly destroyed them and the tread separated causing accidents killing nearly 250 people. If you are not getting the performance from the tire at the recommended pressure... get another tire that is made for what you need.

[Tom1200]

Mike as usual I should have added more detail, these are race tires that I only use for vintage racing and track days.

 

I was curious what some of the other vintage racing guys were running. I know some 510 and Roadster guys use them. I also left out the car is 1778 with me in it.

 

Again the 18-20 hot for my weight car is from Hoosier racing tire distributor. Anecdotally I've also read 1.3 psi per 100lbs which is 23psi. At 22 the car feels my version of a touch tight (note more than one of my competitors has described my car and my driving as alarmingly loose) which means it has mild oversteer. Oversteer = faster laps in a 1200. My lap times were also slightly slower but there are other factors that likely contributed to this; 15 degrees warmer and gusty.

 

Tom

[Duke]

Have you taken tire temps?  Logging tire temps goes a long way in getting suspension setup and pressures right.

[docbainey]

What Duke said.

[G-Duax]

And may I add: Tire temps on the outer edges of the tread, and the center.

 

If the center is running hotter than both edges, then too much pressure, and vise-versa.

[Tom1200]

For the record the tire temps are even all the way across the tire. This is the case at 22 and 24 psi. I posted mainly because I was curious if anyone had noticed a difference in how the tire responded and whether they felt the results were positive. I run a softer set up than most racers (I'm willing to give up the instant feedback for the extra grip) and am very comfortable with tires that have a lot of wind up but at 22 psi, to me, they felt just a tiny bit sluggish.

 

Tom