Tire Pressures

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Beardart

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I took my Swinger to the track last week for some 1/8 miles passes with a new set of 27-10.50 15 Hoosier QT Pros (tubes, no rim screws). I started at 18lbs and worked down to 15lbs. My best 60 was 1.86 with 15lbs but didn't go any lower. I haven't been able to find much information on recommended Hoosier tire pressures. This is a 3200lb street car, frame connectors, S/S springs, snubber and runs low 8.30s (1/8 ) and high 12s (1/4). I know I can get more out of the tires and the car. I also know most of it is trial and error (and track and air conditions ) but, how low can I go on tire pressures? Suggestions?
 
With a tire of that size and car weight I don't think I'd go lower than about 9 or 10 PSI. And even that is probably too low.
 
]keep adding pressure til she spins, then drop back1.5 - 2 lbs . the more pressure you can run= better 60 ft. plus the car will handle better . JMO.
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I ran that tire last year on my Barracuda…about the same weight, with rim screws, running low 11’s. What worked best for my car was 12.5 psi.

You should be fine with a lot more pressure (15+) if you’re running high 12’s. You may want to mark the rim and tire to make sure you’re not spinning the tire on the rim.

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I just got back from Test/Tune this weekend. I was trying to dial in my new Caltrac bars. I started at 16 psi went as low as 12psi and back up to 18psi I ran the same 60 foot at all settings. so I will stick in the 18 psi range. I am running MT ET streets with tubes. I was a little disapointed that I couldnt get more out of my 60 foot time but the track was hot and I think I will now need to go with new rear shocks.
 
Thanks for the suggestions. Last time out I made some passes at 13 and 14 lbs. My ETs were pretty consistent with a best 60' of 1.84. I know these tires should be good for 1.70s but it may be more about the track and track prep (or lack thereof) than about tire pressures.
 
You want to run the highest pressure you can without spinning. Like stated before the car will handle better with higher pressure and you may actually have a better ET and MPH with higher pressures due to lower rolling resistance.


Chuck
 
I run mickey thompson street et radials,started at 18 psi and made my way down to 15psi,which the car seems to like ,it 60's in the 1.40's..another little trick pump the from tires up with air,i run 40psi in mine for less rolling resistence..
 
I run the mt sportsman pros right now and going to switch to drag radials. I was told from harlow tire to lose the tubes get rid of unsprung weight and to take dawn dish soap and smear all over the inside of the tire. Sides and bottom to seal it. Works great! My pros can sit all winter and no leak down. He told that he does that on 8 and 9 sec. car tires.
 
I always ran around 15# in the slicks on my R/T. Last weekend, I started with 20# and ended up netting the best 60' ever. I may try to throw a few more pounds in this next time and see what happens. When it spins, drop down in 1.5 pound increments.
 
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